A qualitative review and integrative model of gratitude and physical health.

Lavelock, Caroline R. ; Griffin, Brandon J. ; Worthington, Everett L., Jr. 等

Gratitude is seen as a central component of Christian theology, and the extant literature suggests that there is an important relation between gratitude and physical health and well-being. In the current review, we summarize 42 studies published since 2009 that inform this relationship. Based on the theoretical framework by Hill, Allemand, and Roberts (2013), we organize our review in three sections that focus on how gratitude influences physical health through (a) mental health, (b) health behaviors, and (c) interpersonal variables. We discuss and integrate the findings from these studies into a theoretical model of gratitude and physical health. In addition to the three mechanisms in the Hill et al. model, we integrate variables from a previously conducted literature review of gratitude and well-being (Wood, Froh, & Geraghty, 2010), and we add personal factors, positive or adverse events, and explicit interventions as antecedents to gratitude in our model. We conclude by discussing future directions for gratitude and health research and its role within Christian psychology.

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Many studies have demonstrated a positive relationship between religious life and physical health (for a review, see Koenig, King, & Carson, 2012). Gratitude, an important aspect of Christianity, may therefore have implications for physical health outcomes. Psychological research on gratitude is an emerging field (Emmons & McCullough, 2003; Wood, Froh, & Geraghty, 2010), yet, despite the spirit of thanksgiving in Christian theology, research integrating gratitude within the framework of Christian theology is sparse (cf. Bassett, 2013; Bland, 2009; Dwiwardani et al., 2014; Emmons & Kneezel, 2005; Kim-van Daalen, 2012). As the body is considered God's temple, it is essential for theology and psychology to examine gratitude within a Christian context as well as to examine the link between gratitude and physical health. In this paper, we aim to move these fields forward as we review recent research on the relationship between gratitude and physical health and consider implications for the Christian faith.

A Christian Understanding of Gratitude

The root of the word gratitude comes from the Latin gratia, referring to "the beauty of giving and receiving" (Pruyser, 1976, p. 69). Consistent with a Christian understanding of gratitude, Emmons and McCullough (2003) conceptualized gratitude as a moral affect. They defined gratitude as "the ability to notice, appreciate, and savor the elements of one's life" (p. 378). Gratitude is an affective reaction to complex cognitions that involve appraising something as good or meaningful. It can be directed toward others, the natural (e.g., nature, beauty), or the supernatural (Emmons & McCullough, 2003).

Christians have many reasons to feel grateful. For example, Psalm 103:1-5 (ESV) says:

   Bless the Lord, O my soul, and forget not all his benefits,
   who forgives all your iniquity, who heals all your diseases,
   who redeems your life from the pit, who crowns you with
   steadfast love and mercy, who satisfies you with good so
   that your youth is renewed like the eagle's.

Christians have the potential for gratitude because Christ acted to relieve guilt over moral failure and to reconcile their relationships with God and with each other (Bethune, 2001). In addition, Christians believe that God adopts them into a family that shares a variety of benefits (Krause, Emmons, & Ironson, 2015), including identity, honor, provision, and love. Thus, Christians have the potential for gratitude when they receive gifts of love from others in the Christian community or from any aspects of creation, which is viewed as a gift from God.

Thankfulness to God and to others might not only promote shalom but also, relatedly, lessen stress. In Colossians 3:15, Paul writes, "Let the peace of Christ rule in your hearts, since as members of one body you were called to peace. And be thankful." If peace and thankfulness are related, we might hypothesize that gratitude is likely to prevent or mitigate stress-related disorders, especially in the later years of life after stress has had more time to ravage the physical systems (Krause, 2006). Thus, gratitude may have a beneficial impact on physical health through its potential ability to mitigate stress.

As such, much of the research on gratitude has focused on its benefits for mental health and well-being (for a meta-analysis, see Wood et al., 2010). Despite early studies by Emmons and McCullough that associated gratitude and physical health, relatively less emphasis has since been placed on benefits to physical health (Wood et al., 2010). Yet, according to the author of the proverb, "A joyful heart does good like a medicine, but a crushed spirit dries up the bones" (Proverbs 17:22), there seems to be a connection between physical, mental, and spiritual health and gratitude. Thus, in integrating Christian theology and psychology, more focus is needed to consider the psychosomatic correlates and effects of gratitude.

Early Research on Gratitude and Physical Health

Gratitude is typically experienced as a positive emotion (Fredrickson, Tugade, Waugh, & Larkin, 2003). This distinguishes gratitude from the conceptually similar indebtedness, which involves obligation, guilt, and duty. Instead, gratitude is linked to contentment (Walker & Pitts, 1998), happiness, healthy (not arrogant) pride, hope (Overwalle, Mervielde, & De Schuyter, 1995), life satisfaction, optimism, empathy, perspective-taking, and positive affect (McCullough, Emmons, & Tsang, 2002). Furthermore, gratitude has been conceptualized as a moral motivator; the experience of feeling gratitude toward people prompts individuals to act benevolently toward them (McCullough, Kirkpatrick, Emmons, & Larson, 2001). As such, gratitude has shown a strong relationship with mental health variables, including decreased psychopathology, less neurotic personality, positive relationships, better well-being, and a humanistic orientation of functioning (Wood et al., 2010). It has also been considered a potential buffer to stress (Fredrickson et al., 2003) and is related to religious involvement, spirituality (McCullough et al., 2002), and prayer (Lambert, Graham, & Fincham, 2009).

Wood et al. (2010) reviewed prior research on gratitude and well-being and found that "almost no studies have been conducted into gratitude and physical health" (p. 896). In examining gratitude and mental health, however, they identified four potential mechanisms by which gratitude could lead to better mental health. Namely, they theorized that gratitude promotes (1) interpretive schemas of acts of others (that is, how one interprets the cost, value, and altruism of another's actions), (2) positive coping, (3) positive affect, and (4) the broadening and building aspect of gratitude as a positive emotion. Though focused largely on exploring gratitude's relation with mental health, Wood et al. identified stress-reduction (Deutsch, 1984; Krause, 2006; Wood, Maltby, Gillett, Linley, 8c Joseph, 2008) as one of two largely researched correlates of gratitude that may explain a hypothesized relationship between gratitude and physical health. Mechanisms in the relationship between stress and poor physical health included immune functioning, difficulty regulating emotions, and poor adherence to healthy coping strategies (Rozanski & Kubzansky, 2005).

The other physical process that has a nuanced relationship with gratitude is sleep. For example, gratitude has been linked with higher amounts of sleep, more refreshment following sleep (Emmons & McCullough, 2003), better sleep quality, less time to fall asleep, and better daytime functionality (Wood, Joseph, Lloyd, & Atkins, 2009). The mechanism primarily affecting this relationship seemed to be the positivity or negativity of thoughts prior to falling asleep. This relationship between duration and quality of sleep with physical and mental health is consistent with recent longitudinal sleep research (Wong, Lau, & Wan, 2013). Thus, as of 2010, the main explanatory links for why gratitude might be related to physical health were the positive nature of gratitude's impact on stress (a mental health factor) and better sleep (a physical health behavior). However, at that time, the exact relationship between gratitude and physical health was inconclusive due to the paucity of relevant research (Wood et al., 2010).

Thus, mental health and physical health behaviors have become the sensible mechanisms of study for gratitude and physical health. In a recent study, Hill, Allemand, and Roberts (2013) investigated a potential model for how gratitude may predict physical health. Survey results from 962 Swiss adults suggested that more grateful individuals reported better physical health, and these effects were mediated by mental health, healthy behaviors, and willingness to seek help for health concerns. Furthermore, the effects of these mediators were stronger as age increased.

Our current review was informed by both the results and the limitations of Hill et al.'s (2013) model. This model is the only existing empirically-based framework examining the relationship between gratitude and physical health. Our primary objective was to extend the field of gratitude by searching for research on the topic of gratitude and physical health conducted since Wood et al.'s (2010) review. Our second objective was to organize this literature according to Hill et al.'s theoretical framework of how gratitude relates to physical health via mental health, healthy behaviors, and willingness to seek help for health concerns. Based on our review, we considered how Hill et al.'s model was supported and also how it required modification.

In this review, we have presented an updated model of gratitude and physical health, which integrates the present literature as well as existing components from Hill et al. (2013) and Wood et al. (2010). In our integrated model, we have operationalized health outcomes as physical symptoms, objective health measures, health behaviors, and physical well-being. Consistent with Hill et al.'s model, as well as a Christian understanding of gratitude, we hypothesized that the reviewed literature would reveal that gratitude has been associated with more positive health outcomes, fewer negative health outcomes, and generally better physical well-being. Our final objective was to then consider how the results of our review and integrative model inform a Christian understanding of gratitude. Our overall purpose was to highlight existing gratitude and health research that has not been integrated into Hill et al.'s theoretical framework, to consider an updated model on gratitude and physical health for greater understanding of gratitude's psychosomatic impact, and to encourage future research in psychology and theology.

Method

As we are extending work by Wood et al. (2010), our review focused on articles published after 2009 (see Figure 1 for selection criteria). We focused our review on 42 articles from PsycINFO and PubMed with relevance to gratitude and physical health (Tables 1, 2, and 3).

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Results

Among these articles, we first identified four literature reviews (summarized in Table 1). We then identified nine purely qualitative and three mixed qualitative and mixed-method papers (see Table 2). After drawing conclusions from those 12 studies, we reviewed the quantitative results (see Table 3) that have accumulated in the last six years. Of the 26 empirical quantitative studies conducted within these publications, 17 were correlational, five were experimental, three were quasi-experimental, and one was retrospective. Most (n = 18) were cross-sectional, but eight quantitative studies were longitudinal.

Summary of Review Papers

The four review papers considered qualitative and quantitative studies related to gratitude (see Table 1). The majority of the studies in these reviews reflected on gratitude as related to positive mental and physical health outcomes. For example, in a qualitative review of 12 empirical studies examining gratitude interventions, Borgueta (2012) noted that two interventions--a written listing exercise and a gratitude letter-writing exercise--received the most empirical support and demonstrated improvement in mood, depressive symptoms, and self-reported happiness. Though none of these reviews focused explicitly on the relationship between gratitude and physical health, Borgueta suggested that gratitude interventions can be effective and have psychosocial and physical health benefits, such as more exercise and fewer physical symptoms.

Methodology of Qualitative and Quantitative Studies

The included empirical studies sampled undergraduates, healthy adults, adults in treatment for physical health concerns (disabled, transplant donors/recipients, cancer patients), health service providers, and children/adolescents. Several studies employed samples collected outside of the United States. From 2003 to 2009, qualitative papers dominated the research on gratitude and physical health (see Wood et al., 2010). Today, the rate of qualitative studies has leveled off (see Table 2), and studies have recently also reported some quantitative results.

Qualitative studies tended to interview people who had suffered some trial in life (e.g., spinal cord injury, organ transplant, dementia). Often, participants spontaneously reported feeling grateful to God or to others or learning from their experiences. Thus, gratitude was repeatedly depicted as a natural response to suffering and physical challenges.

Of the measures employed across these studies, many were comprised of items created for a particular study or selected from existing measures, as opposed to psychometrically-supported measures. Gratitude was most commonly measured with the Gratitude Questionnaire (GQ-6; McCullough et al., 2002), but also with the Gratitude Adjective Checklist (McCullough et al., 2002), the Gratitude Resentment and Appreciation Test--Short Form (GRAT-SF; Watkins, Woodward, Stone, & Kolts, 2003), the Religious Gratitude Questionnaire (Rosmarin, Pirutinsky, Cohen, Galler, & Krumrei, 2011), and single-item measures of gratitude.

Physical health outcomes were most commonly assessed using self-report measures. These included various versions of the Short Form Health Status Survey (Stewart & Ware, 1992), the Health-Related Quality of Life Scale (HRQOL-14; Centers for Disease Control and Prevention, 2000), World Health Organization Health Quality of Life-Brief scale (Murphy, Herrman, Hawthorne, Pinzone, & Evert, 2000), the Somatization subscale of the Brief Symptom Inventory-18 (Derogatis, 2000), the Chronic Pain Grade (CPG) Questionnaire (VonKorff, Dworkin, & LeResche, 1990), and various checklists of physical symptoms and/or other self-reports (e.g., sick days, number of pain medications taken).

Only five studies (Barraza et al., 2013; Kimmerling, 2014; Knowlton et al., 2015; Mills et al., 2015; Zahn, Garrido, Moll, & Grafman, 2014) used objective physiological measures: systolic and diastolic blood pressure, resting heart rate, body mass index, fMRI, viral suppression, and inflammatory biomarkers. Three of these studies were the only reviewed studies to examine a direct link between gratitude and physical health and physiological indicators.

Studies Directly Examining Gratitude and Physical Health

First, in an experimental and longitudinal study of 39 older adults, Barraza et al. (2013) compared a group who received intranasal oxytocin to a control group who received placebo for 10 days. Mood and cardiovascular state did not change in either condition; however, oxytocin seemed to increase trait gratitude and buffer declines in gratitude, physical functioning, and fatigue experienced by the control group over time. Additionally, in a correlational and cross-sectional study of 52 graduate and undergraduate students, Kimmerling (2014) found that gratitude was negatively correlated with diastolic blood pressure, but only when controlling for optimism and Big Five personality factors. The author acknowledged the sample size as too small for results to be conclusive. The third such study demonstrated that gratitude was related to fewer inflammatory biomarkers in a sample of 186 adults with asymptomatic heart failure (Mills et al., 2015). This study will be discussed in greater detail in a later section.

The remaining publications were reviewed through the lens of three mechanisms between gratitude and physical health described by Hill et al. (2013): (1) specific mental health outcomes of gratitude and their impact on physical health outcomes; (2) healthy behaviors related to gratitude and their impact on physical health outcomes; and (3) interpersonal variables, such as willingness to seek help, that are related to gratitude and physical health. We acknowledge that due to our search criteria, research on each of these mechanisms is not exhaustive and represents research in these topics as they relate specifically to physical health.

Specific Mental Health Outcomes

The largest subset of gratitude and health research in this review involves mental health outcomes as related factors and, at times, mediators explaining the relationship between gratitude and physical health. A number of studies supported gratitude's relationship with mental health in addition to physical health (Lambert D'raven, Moliver, & Thompson, 2015; Ng & Wong, 2013). Yet, mental health is a large and varied term. Thus, we have focused further discussion in terms of prominent themes in this literature; positive affect and stress.

Positive affect. Gratitude has frequently been associated with positive affect and inversely associated with depression and negative affect (Koenig et al., 2014). Yet, results in the present review show a nuanced history of gratitude's relationship to affect. For example, in an experimental and longitudinal study, findings for a seminal inquiry of gratitude and physical health (Emmons & McCullough, 2003) were partially replicated in a sample of 105 Spanish undergraduates (Martinez-Marti, Avia, & Hernandez-Lloreda, 2010). State gratitude and positive affect were significantly greater in a gratitude intervention condition than in a daily hassles condition at post-test. However, positive affect seemed to mediate the effect of the gratitude intervention just as much as gratitude did, making positive affect difficult to differentiate from gratitude. Furthermore, no differences were found among conditions in measures of physical well-being, as they had been for Emmons and McCullough (2003).

Conversely, in a correlational, cross-sectional study, Froh, Yurkewicz, and Kashdan (2009) found that gratitude was related to fewer physical symptoms but was unrelated to negative affect in 154 middle school students, inconsistent with most gratitude literature. Instead, gratitude was associated with positive affect, global and domain-specific life satisfaction, optimism, social support, and pro-social behavior; most relations remained even after controlling for positive affect. Though later research would demonstrate a less conflicting relationship between gratitude and affect (as we will see later in this review), these findings may be a result of varying population factors (e.g., age, mental health, physical health status).

Stress. Positive psychological variables such as gratitude have been hypothesized to serve as a buffer against stress and its psychological and physiological effects (Fredrickson et al, 2003; Rozanski & Kubzansky, 2005). Yet, only a very small amount of research in this review examined the relationship between gratitude and stress, and findings have been mixed.

Gavian (2012) randomly assigned 247 undergraduate participants to a gratitude intervention group, a progressive-muscle relaxation group, or a control group. There were no effects of a gratitude intervention on any outcomes, nor did gratitude or PMR improve stress reactivity better than the control group. This suggests gratitude may not be an effective intervention for stress reduction in healthy populations who do not necessarily seek it.

However, other intervention studies (Cheng, Tsui, & Lam, 2015; Tsui, 2012) suggest that this may not be the case. In these experimental, longitudinal studies of 102 adult healthcare providers in Hong Kong, researchers randomly assigned participants either to write about gratitude events or hassle events or to be in the non-action control group over several weeks. The gratitude group ended with higher psychological well-being than the non-action control group, as measured by perceived stress, life satisfaction, positive affect (Tsui, 2012), and depressive symptoms (Cheng et al., 2015). These findings are consistent with the idea that positive thoughts related to gratitude may be a useful way to relieve stress (even coping with a parent's chronic illness; Stoeckel, Weissbrod, & Ahrens, 2015) and prevent depressive and anxious symptoms.

Additionally, interventions targeting mental and physical health may impact gratitude. In a study by Lamke, Catlin, and Mason-Chadd (2014), 20 nurses were subjected to a month-long self-care regimen called Jin Shin Jyutsu", in which awareness is heightened of the self s ability to balance and release physical, mental, and spiritual tension using actions of the body. Participants reported significant increases in gratitude and other markers of well-being at post-test, including decreased stress, as well as better care for their patients. If mental and physical self-care can contribute to gratitude, perhaps the relationship between gratitude and mental and physical health may be bi-directional or cyclical.

Health Behaviors

Health behaviors range from engaging in physical activity to maintaining a healthy diet, avoiding unhealthy habits (e.g., substance abuse), and getting enough sleep. In this review, physical activity, sleep, and self-care emerged as the prominent themes of health behaviors potentially related to gratitude.

Physical activity. Though seminal research conducted by Emmons and McCullough (2003) demonstrated a link between exercise and gratitude, several studies in the present review suggest this may not be the case, particularly in non-healthy populations. For example, Huffman et al. (2014) collected qualitative and quantitative data in a longitudinal study of 34 acute coronary syndrome patients. Though gratitude was commonly reported, it was infrequently associated with health behaviors such as healthy eating and physical activity. Additionally, Kimmerling's (2014) aforementioned study of 52 students found no relationship between gratitude and exercise frequency, nor did gratitude relate to tobacco use or alcohol consumption. However, as aforementioned, the sample size was considered too small to be conclusive.

A reasonable proposition regarding the relationship between gratitude and exercise comes from Plunkett's (2012) correlational, cross-sectional study of 30 transplant recipients. Two of the six categories of themes described in successful post-organ transplant life were physical activity and gratitude. These were seen as co-occurring byproducts of successful post-transplant living, rather than as causally related . This may be the case in such clinical populations.

Sleep. Ng and Wong (2013) studied gratitude and sleep in 224 Chinese chronic pain patients. In this correlational and cross-sectional inquiry, insomnia correlated positively with chronic pain symptoms, and higher gratitude was associated with better sleep and lower depression. Amount and quality of sleep partially mediated the relationship between gratitude and anxiety but not between gratitude and depression. Overall, participants who reported better sleep had less depression and anxiety, and better sleep was associated with higher gratitude. This supports Emmons and McCullough's (2003) evidence of sleep's implication in the gratitude and health relationship; however, it places sleep in a mediational role between gratitude and mental health, rather than as a more direct mechanism to achieve better physical health.

Borgueta (2012) also considered the relationship between gratitude and sleep in her qualitative review of gratitude interventions. For example, in a study examining placebo therapy (Hyland, Whalley, & Geraghty, 2007), a gratitude exercise was implemented as a placebo in the study of a sleep intervention. Trait gratitude was associated with better sleep quality. Borgueta concluded from such studies that improved sleep could be a benefit of gratitude.

Self-care. Some studies in this review described participants' motivation to engage in health behaviors that reflected their gratitude for their new hope to live. For example, semi-structured interviews of six long-term cancer survivors yielded gratitude for both life and survival as themes related to post-traumatic growth (Frye, 2014). Participants also reported improved self-care and health behaviors, including attending doctors' appointments, modifying diet, tracking symptoms attentively, and getting plenty of rest. Though qualitative and without implications for causality, these two studies are consistent with the hypothesis that gratitude may improve health behaviors that demonstrate one's gratitude for a second chance at life.

Similarly, Tong Morton, Howard, and Craig (2009) conducted a qualitative review of 18 qualitative studies exploring adolescents' experiences with organ transplantation. Participants' desire to maintain health status via healthy behaviors and medical regimen was common. However, behaviors were not always charged with gratitude and positive affect, but rather obligation, burden, and the fear of neglecting their medical regimen. These may contribute to rumination about deservingness in organ transplant recipients (O'Brien, Donaghue, Walker, & Wood, 2014). Such findings may explain equivocal results in quantitative studies examining the role of positive affect as a mediator of the relationship between gratitude and physical health.

Interpersonal Variables

A large portion of the current research comes from qualitative inquiries following illness and medical procedures. As such, the subset of gratitude and health literature pertaining to interpersonal variables, such as willingness to seek help from others, can be divided into the following categories: gratitude as a result of physical health adversity as discussed in Hill et al. (2013), and gratitude and health in healthy populations.

Interpersonal variables as a result of physical health adversity. Frye's (2014) qualitative inquiry illustrates Hill and colleagues' (2013) concept of cancer patients who are grateful to be alive and their willingness to seek help for health concerns by prioritizing doctor's appointments. However, the focus of gratitude as a result of physical health adversity also tends to be directed toward others, especially caretakers, donors, health care providers, and spiritual/existential targets such as God (O'Sullivan & Chard, 2010; Tong et al., 2009). For example, Knowlton et al. (2015) conducted a correlational and cross-sectional study of 258 HIV patients and 258 of their informal caretakers; results indicated that caretakers' reports of treatment adherence showed high concordance with actual viral suppression in relationships with higher affection and gratitude. Furthermore, participants' physical limitations were associated with low concordance between caregiver report and viral suppression. This suggests that reciprocal gratitude in the caretaking relationship may promote a functional caregiving relationship, which can be vital to promoting and maintaining positive physical health outcomes.

Even donors and formal health care providers have been studied in the gratitude literature (Dijker, Nelissen, & Stijnen, 2013; Stevens, Barlow, & Iliffe, 2015). For example, Fries, Bowers, Gross, and Frost (2013) had 18 professionals-in-training (students in nursing, occupational therapy, or physical therapy) complete qualitative measures about providing health care services for a week in Guatemala. Participants reported feeling grateful for the opportunity to provide health services with colleagues. This study suggests that gratitude may operate cyclically in the health care environment; health care providers offer patients help, and patients are grateful toward health care providers, making health care providers grateful to help.

Gratitude may also involve God, spirituality (i.e., a relationship with the sacred), and existential factors (i.e., contemplation about the value and duration of one's life). For example, in a qualitative study interviewing nine Latino adolescent cancer survivors, the following themes emerged: gratitude for life and for those who had helped them, empathy for younger children with cancer, God and faith, cancer as meaningful and life-changing, family support, and relationships with medical staff (Jones et al., 2010).

Interpersonal variables in healthy populations. In this category of gratitude research examining interpersonal variables, a variety of everyday relationships are at the focus. In a previously described study of middle school students, relational fulfillment mediated the relation between gratitude and physical symptoms (Froh et al., 2009). The relation between gratitude and family support was moderated by gender; girls tended to report more gratitude than boys, but compared with girls, boys appeared to derive more social benefits from gratitude.

A later study focused more on the role of one's relationship with God on gratitude and physical health (Krause et al., 2015). In this correlational, cross-sectional study of 1774 adults, those with higher attendance at worship services tended to have more benevolent images of God; this was mediated by higher spiritual support from other congregants. Those with more benevolent God-images felt more gratitude toward God; greater gratitude to God was associated with hope for the future, which was associated with better self-rated health and fewer physical health symptoms. Interestingly, spiritual support alone was associated with more physical symptoms; the authors suggest that spiritual support may cause stress when it is not desired. In other words, it may be that when people are not grateful for the help of others, they experience less desirable physical outcomes. Overall, we see that both the spiritual companionship of others and images of God as benevolent seem related to positive physical health outcomes via gratitude.

Successful aging, as described in a study by Pietrzak, Tsai, Kirwin, and Southwick (2014), can be considered in interpersonal terms as well. In that study of 2,025 veterans, one of the components of successful aging was social functioning. Physical health difficulties and current psychological distress were most strongly negatively related to scores on this composite of successful aging. In addition, resilience, gratitude, purpose in life, and community integration were most strongly positively related to successful aging, perhaps demonstrating their protective value in the existential, spiritual, relational experience of aging.

Pan-Thematic Studies

Two studies encompassed most subdivisions of the present review. A recent longitudinal study employing both quasi-experimental quantitative and qualitative methods sampled 27 Canadian adults with depression (Lambert D'Raven et al., 2015). Following a 6-week program to promote happiness (including activities such as gratitude letters and altruistic acts), participants showed improvement in both physical and mental health outcomes, including lower depression, lower perception of pain, greater vitality, better mental health, positive effects of mental and physical health on daily activities, greater energy, better social functioning, more accomplishments each day, and reduced functional limitations. Qualitative interviews revealed experiences such as resisting a cold, spending more time with family, being grateful for every day, thoughts of a bright future, and enjoying work more following the intervention. In this study, it remains unclear whether positive physical health outcomes resulted from gratitude, or if both gratitude and physical health resulted from some other common factor (e.g., positive affect).

A later correlational, cross-sectional study of 186 adults with asymptomatic heart failure sheds light on that question (Mills et al., 2015). Spiritual well-being and gratitude were associated with fewer depressive symptoms, better sleep, better self-efficacy for self-care related to cardiac functioning, and less fatigue. Gratitude was also associated with fewer inflammatory biomarkers. Further analysis determined that gratitude fully mediated spiritual well-being's relationships with sleep quality and depression and partially mediated spiritual well-being's relationships with fatigue and self-efficacy. Mills et al. (2015) noted that the prevention of depression and improved sleep can prevent more severe physiological symptoms associated with advancing heart failure. These studies illustrate the mental, health-behavior, interpersonal/ spiritual, and physiological mechanisms that allow gratitude to result in positive physical health outcomes, and Mills et al. suggest that it may be gratitude's unique and eudaimonic (i.e., not hedonistic) positive reappraisal of stressful events that results in reduced inflammation.

Discussion

In this review, gratitude was generally associated with positive mental and physical health outcomes with occasional null findings but virtually never with negative outcomes when true gratitude (i.e., not obligation) was in question. Instances of inconsistency may be due to the use of measures without psychometric validation, differences in the nature and dosage of gratitude interventions (Borgueta, 2012), differences in healthy and unhealthy populations, and confounding variables that have not yet been thoroughly examined. Though improved methodology will reveal the most accurate relationships between gratitude and the variables in question, these findings have promise for how gratitude may serve positive physical health.

Overall, the gratitude and physical health literature is methodologically diverse given the novelty of the topic. Various research designs have been used, and a fair proportion have accessed international and non-undergraduate samples. The major limitation in this field of research is that many studies used measures created by the authors rather than psychometrically validated scales. In this section, we first reflect on an integrative model for representing the relationships between gratitude and health. We then speculate about possible theoretical connections involving religion and spirituality. Finally, we suggest a research agenda for Christian variables and their intersection between gratitude and health.

Qualified Support for Hill et al.'s Model of Gratitude and Physical Health

The reviewed literature provides further evidence for each component of Hill et al.'s (2013) model of gratitude and physical health. The bulk of this research assessed mental health as a mechanism for the gratitude and physical health relationship. Specifically, gratitude appears to be related to, but unique from, undifferentiated positive affect, perhaps because it can arise from perceiving a benefit even under stressful circumstances involving meaning-making, social and moral implications, and a myriad of emotions. This distinction between gratitude and positive affect is consistent with research outlined in Wood et al.'s (2010) review, in which positive affect did not fully explain the relationship between gratitude and physical health. It is also consistent with a Biblical understanding of virtue, which is often enacted in a time of trial, stress, and suffering (most notably the crucifixion of Jesus). Thus, virtues such as gratitude may not always result from the most pleasant circumstances, but gratitude's eudaimonic positivity is meaningful, moral, and even associated with stress reduction.

Next to mental health outcomes, relational outcomes were the most prevalent theme in this literature, perhaps because gratitude is often focused outward to others or to life circumstances. Prominent themes in this literature were exhibited within the health profession (as experienced among patients, their families, and their health care providers), in relationships outside of the health care setting, and in healthy populations. The interpersonal implications of gratitude also seem to include existential factors and spiritual relationships, particularly as they relate to the meaning and value of life and perceived blessings. This too is consistent with previous literature, as gratitude has been previously conceptualized as an aspect of spirituality (Koenig, 2008) and the Christian religion, which is at its core, relational (e.g., Mark 12:31).

By far, the least amount of research in the present review focused on the relationship between gratitude and physical health behaviors. While less evidence supports gratitude's relation to physical activity, evidence has surfaced in favor of both sleep and concerted efforts to care for one's health as potential mechanisms explaining gratitude's relationship to physical health (Borgueta, 2012). Furthermore, both willingness to seek help--which can be considered a relational variable as well as a health behavior if help is being sought for a health concern--and spirituality have support for being related to gratitude. However, results surrounding gratitude's relationships to physical health behaviors are highly inconclusive, and little research exists on spirituality as a factor related to gratitude and physical health, despite gratitude's theological underpinnings.

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We conclude that Hill et al.'s (2013) proposed model of gratitude and physical health has been largely supported by the research in this review. Thus, we maintain Hill et al.'s framework moving forward, with the addition of potential mechanisms that may provide future directions for clarifying relationships in which results thus far have been conflicting.

Integrative Model of Gratitude and Physical Health

We propose a comprehensive, integrative model for gratitude and health informed by recent years of literature (Figure 2). The model posits that gratitude is influenced by personal factors (e.g., grateful personality, other character strengths, religion, spirituality, and willingness to seek help for health concerns or otherwise), events (e.g., a gift or unexpected blessing, or alternatively, an adverse circumstance such as stress or illness), and explicit interventions to promote gratitude (e.g., gratitude journaling). The model also posits that gratitude influences health through three mechanisms, which we modified from Hill et al. (2013): promotion of positive mental health outcomes (e.g., positive affect, decreased stress, higher life satisfaction), health behaviors (e.g., taking care of oneself, better sleep hygiene), and relational outcomes (e.g., better relationship quality with others and the Sacred, perceived social support). Due to little research implicating causality in the literature, we used double-sided arrows in our model, even between gratitude and personal factors, in the interest of remaining open to bi-directional relationships and correlations (e.g., being grateful might predispose one to experience events that prompt gratitude).

Inconsistent findings in the current literature may be based on age of population (as suggested by Hill et al., 2013); findings from young adult populations are not always consistent with findings from older adult populations, especially in relation to mental health and to health behavior mechanisms between mental and physical health. Sex too seems to show preliminary differences in relational outcomes related to gratitude. We cannot definitively determine the sex breakdown of the studies in this review because not all studies reported this demographic, but we have chosen to maintain it as a potential moderator in gratitude's relationship to health.

Although we began with a modified model that drew on Hill et al. (2013), we have incorporated substantial additions from other theories and from research. For example, we incorporated aspects of Wood et al.'s (2010) model of gratitude and mental health, such that coping strategies, interpretive schemas, broadening and building, and positive affect (presented together in the model in the interest of space) impact mental health. Because these factors were not the focus of the present review, we cannot confidently posit that they also impact health behaviors and relationships, and thus physical health. Such relationships represent an area that is ripe for future research. Finally, we have included several potential physical health outcomes not incorporated in other models, including improved physiological functioning, better sleep, more physical activity, fewer inflammatory biomarkers, and more oxytocin--a hormone that indicates interpersonal bonding. Overall, we believe that our more comprehensive model of gratitude and health is more complete than other models and also provides more opportunities for expansion.

Implications of Current Literature for a Christian Understanding of Gratitude

Conceptualizations of gratitude as an element of moral character provide Christian scholars with a unique opportunity to integrate the scientific study of gratitude with theology, especially doctrines pertaining to how the nature of God is reflected by people in the context of Christian community. If gratitude is an element of virtuous character, what might the implications of Christian theology be for the empirical study of gratitude?

First, Scripture is clear that God has revealed himself as gracious, giving a variety of good gifts, favor, and honor to humans. The appropriate response to divine generosity is gratitude and joy, not indebtedness and attempts to earn grace or somehow reciprocate. Indeed, one of the oldest teachings of the Christian church, the satisfaction theory of atonement, states that Christ's sacrifice is not intended to indebt people to God but to free people from their debt of sin (Eddy & Beilby, 2006). Thus, in order to perpetuate integration between psychological and theological study of gratitude, studies are needed to clarify personal and contextual factors that may hinder someone's ability to experience gratitude. We hypothesize that, while gratitude has been linked to positive health outcomes, feelings of indebtedness (religious, spiritual, or otherwise) are likely linked to increased stress-related health problems and decreased positive emotion. Grace may thereby be implicated as a mechanism for the ability to experience gratitude.

Second, in the person of Christ, the relational nature of God was revealed, as Jesus repeatedly expressed his gratitude to God the Father. The theological significance of unity between members of the Trinity--the Father, Son, and Spirit--is analogous to people being destined for life in community, as people are created in the relational image of God (Genesis 1:27). Not surprisingly, preliminary empirical evidence suggests that the benefits of gratitude may not be fully realized without the outward expression of one's gratitude to others (Lambert, Clark, Durtschi, Fincham, & Graham, 2010). While many studies of gratitude focus on one's subjective feelings for gratitude, future research may illuminate the psychophysiological benefits associated with gratitude that might be intensified if one's gratitude were expressed interpersonally or to God. Furthermore, gratitude among fellow Christians within Christian congregations might be related to physical health in affecting mental health, relationships, social support, and encouragement in spiritual growth and development.

Third, Scripture reveals the importance of gratitude in situations that are perceived as difficulties in life not just in positive experiences (1 Thessalonians 5:18). For example, even as Job mourned the loss of his health, family, and estate, he blessed the name of the Lord (Job 1:21). As demonstrated in the present review, the science of gratitude has already capitalized on gratitude in the midst of adversity. Future studies of gratitude should continue to focus on the physical health functions of gratitude in negative circumstances and how they may differ from gratitude under conditions of pleasure. Finally, Scripture is clear that gratitude occurs not in isolation, but as part of an array of attributes that constitute virtuous character (Galatians 5:22-23). The next wave of empirical research on gratitude may benefit from heeding the message of Scripture to examine other virtues (i.e., humility, love) that support experiences of gratitude.

Ultimately, gratitude is viewed in the Christian tradition as one of many possible virtuous responses in times of wellness and adversity, and it has been considered as a mechanism for nurturing the body as God's temple. Though Christianity can be subtle or difficult to see in the reviewed research, our integrative model parallels this theological claim, in that much of the literature supports gratitude as related to positive physical health outcomes. Additionally, the ways in which our integrative model posits that gratitude impacts physical health (mental health, health behaviors, and interpersonal relationships) also mirrors ways in which Christians attain spiritual health and become one with the Body of Christ--through one's own spiritual being, one's acts/behaviors (attending church services, virtuous works), and one's relationships with God and with religious communities. More explicit study of these specific concepts as they relate to gratitude and physical health is warranted. The reviewed gratitude and physical health literature, as well as the above conceptual and empirical considerations of gratitude research and future studies relative to the Christian faith, can inform both theological and psychological understanding of gratitude and physical health.

Limitations and Future Directions for the Integrative Model

Though we have initial support for our integrative model of gratitude and physical health, more research surrounding the model and each component is merited. Affect and health behaviors in particular seem to be nuanced in gratitude and should be explored; mediators in the relationship between gratitude and mental health suggested by Wood et al. (2010) should be more directly examined in terms of their role in the relationship between gratitude and physical health. Additional research on sex, gender, health status, and gratitude are also valuable future directions to pursue, as these may provide insight into the inconsistent results found in many components of the model. Gratitude's impact on recovery from illness should also be researched further, as should the impact of gratitude's expression and receiving gratitude. Additionally, future studies should examine what makes gratitude interventions work, what kind of populations they work for, and what else can be done to make them more efficacious for improving not only the experience of gratitude, but also mental and physical health outcomes.

Future research should not shy away from illuminating ill-effects of gratitude. Someone extremely high in trait gratitude may be vulnerable, at times, to exploitation if they are not also able to detect manipulation and exploitation in their relationships. For example, gratitude is theorized to strengthen social bonds, which may make it difficult to establish boundaries because they feel intense gratitude for a gift given in the past. Thus, research should explore how gratitude may influence other key relationship variables such as assertiveness and voice.

Finally, the greatest critique of the gratitude research in this review involves the use of non-psychometrically tested measures. This limits the implications and authority of the results and conclusions of the current literature. Objective health measures, such as blood pressure, vagal tone, cortisol levels, cardiovascular, and immune functioning are nearly absent from this literature and should be included as outcome measures. Though representative in some ways, samples for this research should be more diversely sampled, particularly in health-related populations. Sample sizes should also be larger, as many of the studies in the current review are qualitative in design and therefore sample a very small number of participants.

Conclusion

Gratitude and health research has taken a promising upturn in recent years. Based on the reviewed literature and theological considerations, gratitude appears to be a potentially positive and protective factor in its relation to physical health, demonstrating its initial utility for a more positive life experience as a virtue, coping mechanism, and relationship strengthener, with one another and with God. Thus, we have proposed an integrative model of gratitude and physical health in which positive mental health outcomes, positive health behaviors, and positive relational outcomes connect gratitude to positive physical health outcomes. We have encouraged future applications and considered further integration of this model with religious and spiritual factors and the Christian perspective at large. Future research will refine its most important outcomes and implications.

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Caroline R. Lavelock, Brandon J. Griffin, Everett L. Worthington, Jr., Eric G. Benotsch, Yin Lin

Virginia Commonwealth University

Chelsea L. Greer

Spring Hill College

Rachel C. Garthe, Jennifer A. Coleman, and Chelsea M. Hughes

Virginia Commonwealth University

Don E. Davis

Georgia State University

Joshua N. Hook

University of North Texas

Author Note: We want to express our gratitude to the John Templeton Foundation Grant #15627 for contributing the funding toward the current project that made it possible. The opinions expressed in this publication are those of the author(s) and do not necessarily reflect the views of the John Templeton Foundation.

Correspondence concerning this article should be addressed to Caroline R. Lavelock, Virginia Commonwealth University, Richmond, VA 23284. Email: lavelockc@vcu.edu

Author Information

LAVELOCK, CAROLINE R. MS. Address: 806 West Franklin Street, PO Box 842018, Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284. Title: Doctoral candidate (Counseling Psychology) Virginia Commonwealth University. Degrees: MS (Counseling Psychology) Virginia Commonwealth University. Specializations: positive psychology, interventions designed to promote virtue, patience.

GRIFFIN, BRANDON J. MS. Address: 806 West Franklin Street, Department of Psychology, Virginia Commonwealth University, Richmond, VA 23284. Title: Doctoral candidate (Counseling Psychology) Virginia Commonwealth University. Degrees: MS (Counseling Psychology) Virginia Commonwealth University.

WORTHINGTON JR., EVERETT L. PhD. Address: Virginia Commonwealth University, 806 West Franklin Street, P.O. Box 842018, Richmond, VA 23284. Title: Professor of Psychology. Degrees: PhD (Counseling Psychology) University of Missouri-Columbia. Specializations: forgiveness, humility, religious/spiritual interventions, Hope-Focused Couple Approach.

BENOTSCH, ERIC G. PHD. Address: Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, Richmond, VA 23284. Title: Associate Professor of Psychology. Degrees: PhD (Psychology) University of Iowa.

LIN, YIN. MS. Address: Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, Richmond, VA 23284. Title: Doctoral candidate (Counseling Psychology) Virginia Commonwealth University. Degrees: MS (Counseling Psychology) Virginia Commonwealth University.

GREER, CHELSEA L. PhD. Address: Department of Psychology, Spring Hill College, 4000 Dauphin Street, Mobile, AL 36608. Title: Assistant Professor. Degrees: PhD (Counseling Psychology) Virginia Commonwealth University; MA (School & Community Counseling) MSU. Specializations: forgiveness for offenses committed within religious communities.

GARTHE, RACHEL. C. MS. Address: Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, Richmond, VA 23284. Title: Doctoral student (Counseling Psychology) Virginia Commonwealth University. Degrees: MS (Developmental Psychology) Virginia Commonwealth University.

COLEMAN, JENNIFER. A. MA. MS. Address: Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, Richmond, VA 23284. Title: Doctoral candidate (Counseling Psychology) Virginia Commonwealth University. Degrees: MA (Mental Health Counseling) Boston College; MS (Counseling Psychology) Virginia Commonwealth University.

HUGHES, CHELSEA. M. MS. Address: Department of Psychology, Virginia Commonwealth University, 806 West Franklin Street, Richmond, VA 23284. Title: Doctoral student (Counseling Psychology) Virginia Commonwealth University. Degrees: MS (Counseling Psychology) Virginia Commonwealth University.

DAVIS, DON E. PHD. Address: College of Education, Georgia State University, 30 Pryor Street, Room 950, Atlanta, GA 30303. Title: Assistant Professor of Psychology. Degrees: PhD (Counseling Psychology) Virginia Commonwealth University; BA (Psychology) Yale University. Specializations: humility, forgiveness, positive psychology, religion/spirituality.

HOOK, JOSHUA, N. PHD. Address: University of North Texas, 1155 Union Circle #311280, Denton, TX 76203. Title: Assistant Professor of Psychology. Degrees: BS (Psychology) University of Illinois at Urbana-Champaign; MS (Counseling Psychology) Virginia Commonwealth University; PhD (Counseling Psychology) Virginia Commonwealth University. Specializations: positive psychology, humility, forgiveness, religion/spirituality, multicultural counseling.

TABLE 1
Summary Table for 4 Review Articles from 2009 to 2015 on Gratitude
and Physical Health Research (not including Wood, Froh,
& Geraghty, 2010)

                           Participants
Citation               (# female, mean age)        Method   Measures

Tong, Morton,     18 qualitative studies           Review   None
Howard, &         exploring 313 adolescents'
Craig, 2009       experiences with organ
                  transplantation

Borgueta, 2012    12 empirical studies of          Review   None
                  gratitude interventions

DuBois, Beach,    Literature addressing the        Review   None
Kashdan, Nyer,    relationship between positive
Park, Celano, &   psychology attributes and
Huffman, 2012     cardiac outcomes, mechanisms
                  in this relationship, and
                  interventions that target
                  this relationship

Citation                              Conclusions

Tong, Morton,     Five themes emerged from these studies: (1) new
Howard, &         identity, (2) family support, (3) adjusting
Craig, 2009       socially, (4) maintaining health status with
                  medical regimen, and (5) attitude toward the donor,
                  including gratitude as an anxiety-provoking
                  obligation to living donors. Being able to balance
                  and address all of these themes may be essential
                  for mental health.

Borgueta, 2012    Two interventions--a written listing and a writing
                  exercise--received the empirical support
                  demonstrated improvement in mood, symptoms, and
                  happiness Dispositional gratitude, baseline
                  positive affect,  of motivation participants'
                  responses interventions This suggests that
                  interventions can effective and psychosocial and
                  health benefits, exercise, better  and fewer
                  symptoms

DuBois, Beach,    The reviewed literature suggests a relationship
Kashdan, Nyer,    between positive psychological attributes and
Park, Celano, &   cardiac health outcomes. Particularly, gratitude
Huffman, 2012     has been associated with lower anxiety and lower
                  envy. Interventions to promote gratitude have
                  included counting blessings, writing a gratitude
                  letter, benefit finding. Such interventions may
                  decrease depression, and in cardiac populations,
                  preliminary data suggests improvements in mood,
                  anxiety, happiness, and well-being.

Citation                           Future Directions

Tong, Morton,     Future studies should include considerations
Howard, &         of adolescents' relationship with other
Craig, 2009       transplant recipients, need for information,
                  and support garnered online. Multidisciplinary
                  interventions for this population should be
                  explored and tested in order to aid in physical,
                  mental, emotional, and social needs, not just for
                  the adolescents, but for their families.

Borgueta, 2012    Gratitude interventions should continue to be
                  researched, improved, and implemented in a clinical
                  setting.

DuBois, Beach,    Future research should explore the strength and
Kashdan, Nyer,    specificity of the relationship between positive
Park, Celano, &   psychological attributes and health, as well as
Huffman, 2012     the effect of positive psychology interventions on
                  health outcomes, especially in cardiac patients.

TABLE 2
Summary Table for 12 Qualitative and Method Gratitude and Health
Research Articles from 2009 to 2015

                          Participants
Citation              (# female, mean age)            Method

Jones, Volker,     9 Latino adolescents (7;      Qualitative;
Vinajeras,         not reported) who had         cross-sectional
Butros,            survived cancer following
Fitchpatrick, &    diagnosis 2-6 years prior
Rossetto, 2010

O'Sullivan &       5 older Irish adults          Qualitative;
Chard, 2010        (2; 74.4) living in the       cross-sectional
                   community following a
                   stroke in the preceding
                   year

Fries, Bowers,     18 graduate and               Qualitative;
Gross, & Frost,    undergraduate                 longitudinal
2013               students (17; not
                   reported) from nursing,
                   occupational therapy,
                   and physical therapy
                   programs participating
                   in interprofessional
                   collaboration in a service-
                   learning environment
                   (providing health-care
                   services for a week in
                   Guatemala)

Kim, 2013          47 Korean American            Qualitative;
                   firstborn or only sons        cross-sectional
                   and 12 siblings (7; not
                   reported)

Rahmani &          27 Afghani adults (not        Qualitative;
Brekke, 2013       reported; not reported)       cross-sectional
                   involved in the obstetrics
                   process (pregnant women,
                   new mothers, doctors,
                   midwives, and birth
                   attendants)

Frye, 2014         6 older adults (5; 74) who    Qualitative;
                   had some type of cancer       cross-sectional
                   for over 10 years

Huffman,           34 patients (12; 63.4) with   Qualitative and
DuBois,            acute coronary syndrome       correlational;
Mastromauro,                                     longitudinal
Moore, Suarez,
& Park, 2014

Lambert D'raven,   27 Canadian adult             Quasi-
Moliver, &         primary health care           experimental
Thompson,          patients (27; 54)             and qualitative;
2015               with depression               longitudinal

O'Brien,           13 heart transplant           Qualitative;
Donaghue,          recipients (5; 56.23) in      cross-sectional
Walker, &          Australia
Wood, 2014

Sacco, Park,       111 patients (44; not         Qualitative and
Suresh, &          reported) living with         correlational;
Bliss, 2014        advanced heart failure        longitudinal

Stevens, Barlow,   10 British peer mentors       Qualitative;
& Iliffe, 2014     (9; 69) from an exercise      cross-sectional
                   program for older adults

Bailey,            9 adults (5; 38.56) from      Qualitative;
Gammage,           Southern Ontario with         cross-sectional
van Ingen, &       spinal cord injury
Ditor, 2015

Citation                 Measures                  Conclusions

Jones, Volker,     Semi-structured         Seven themes emerged from
Vinajeras,         interviews assessing    participant interviews:
Butros,            for participants'       (1) gratitude for life and
Fitchpatrick, &    experience with and     for those who had helped
Rossetto, 2010     meaning of surviving    them, (2) humor/positive
                   cancer                  attitude, (3) empathy for
                                           younger children with
                                           cancer, (4) God and faith,
                                           (5) cancer as meaningful
                                           and life-changing, (6)
                                           family support, and (7)
                                           relationships with medical
                                           staff.

O'Sullivan &       Semi-structured         Re-engaging in leisure
Chard, 2010        interviews assessing    activities, accepting
                   for post-stroke         physical limitations,
                   experiences             being grateful for help
                                           and support while feeling
                                           so dependent on others,
                                           and looking forward to the
                                           future emerged as themes
                                           from participant
                                           interviews. Post-stroke
                                           interventions may benefit
                                           from more focus on
                                           returning to leisure and
                                           home life sooner following
                                           stroke.

Fries, Bowers,     Written narratives      Participants reflected
Gross, & Frost,    of experiences with     positively on their
2013               service-learning        experiences in Guatemala,
                                           particularly in terms of
                                           interprofessional
                                           collaboration and
                                           appreciation/understanding
                                           of other health care
                                           systems. Participants
                                           reported feeling gratitude
                                           for the opportunity to
                                           provide health services
                                           with other colleagues.

Kim, 2013          Semi-structured         Gender roles, traditions,
                   interview assessing     culture, and parental
                   the health and          expectations are all
                   experience of           important factors when
                   Korean Americans        considering the overall
                                           health of a Korean
                                           American firstborn or only
                                           sons. They encounter
                                           various privileges and
                                           burdens throughout their
                                           lives, but the clash of
                                           Korean and American
                                           cultural differences can
                                           manifest these privileges
                                           and burdens as stressful.
                                           Some participants
                                           expressed gratitude for
                                           the high expectations they
                                           are expected to uphold.

Rahmani &          Semi-structured         Pre-natal health care
Brekke, 2013       interviews              conditions in Afghanistan
                   * For patients, the     were described by
                     interview assessed    participants, both doctors
                     pregnancy and         and patients, with serious
                     health-care           concerns. However, most
                     experiences.          women still expressed
                   * For health care       gratitude for having even
                     professionals, the    the little access to
                     interview assessed    health care that they
                     knowledge of          currently receive, and
                     regulations and       health care professionals
                     quality of the        still experienced pride
                     health care system.   and enjoyment in their
                                           work.

Frye, 2014         Semi-structured         Four major themes were
                   interview               identified by
                                           participants: (1) Cancer
                                           as Trauma, (2)
                                           Relationship with the
                                           Medical Profession, (3)
                                           Normality in Cancer
                                           Survivorship, and (4)
                                           Cancer Changed Me. Among
                                           sub-themes in Cancer
                                           Changed Me were
                                           expressions of positive
                                           growth, including:
                                           Increased appreciation for
                                           life/gratitude, Changed
                                           priorities and keeping
                                           things in perspective,
                                           Growth in personal
                                           strength and self-
                                           confidence, Increased
                                           caring for others/
                                           altruism, Increased
                                           spirituality, and Taking
                                           care of oneself and
                                           improved health behaviors.

Huffman,           * Semi-structured       Optimism and positive
DuBois,              interview             affect were associated
Mastromauro,       * 3 items from the      with physical activity and
Moore, Suarez,       Medical Outcomes      healthy eating. Gratitude
& Park, 2014         Study Specific        was the most commonly
                     Adherence Scale       expressed construct in
                   * Medical record        interviews but was
                     review                infrequently associated
                                           with health behaviors.

Lambert D'raven,   * Short-Form Health     In repeated measurements
Moliver, &           Survey                following a 6-week program
Thompson,            (SF-12--Version 2)    to promote happiness via
2015               * Focus groups          gratitude letters,
                     assessing             altruistic acts, etc.,
                     experience of the     participants showed
                     positive psychology   improvement in physical
                     intervention          and mental health
                                           outcomes. Among these
                                           improved outcomes were:
                                           better self-reported
                                           health, lower depression,
                                           lower perception of pain,
                                           higher vitality, better
                                           mental health, positive
                                           effects of mental and
                                           physical health on daily
                                           activities, greater
                                           energy, better social
                                           functioning, more
                                           accomplishments each day,
                                           and reduced functional
                                           limitations. Qualitative
                                           interviews revealed
                                           experiences such as
                                           resisting a cold, spending
                                           more time with family,
                                           being grateful for every
                                           day, thoughts of a bright
                                           future, and enjoying work
                                           more.

O'Brien,           Semi-structured         Three themes emerged from
Donaghue,          interview               the interviews: (1)
Walker, &                                  deservingness, (2)
Wood, 2014                                 gratitude along with mixed
                                           positive and negative
                                           emotions, and (3) giving
                                           forward. These support a
                                           conceptualization of organ
                                           transplants as a donation,
                                           implicating deservingness,
                                           rather than a gift, which
                                           implicates reciprocity
                                           that is generally not
                                           possible for organ
                                           transplants.

Sacco, Park,       * Semi-structured       Gratitude was positively
Suresh, &            interview             correlated with positive
Bliss, 2014        * Brief                 meaning, social support,
                     Multidimensional      religion/spirituality, and
                     Students' Life        medical resources.
                     Satisfaction Scale    Gratitude was more
                     (BMSLSS)              frequently expressed for
                   * Perceived Personal    social support and meaning
                     Meaning Scale         than for medical resources
                   * Short-Form Health     and physical condition.
                     Survey (SF-12)        Positive meaning and
                   * Center for            religion/spirituality were
                     Epidemiological       inversely correlated with
                     Studies Depression    symptoms of depression and
                     Scale (CES-D)         death anxiety. Social
                   * Satisfaction with     support was correlated
                     Life Scale (SWLS)     with higher death anxiety
                   * Death and Dying       at 3-month follow-up.
                     subscale from the     Meaning and gratitude may
                     World Health          alleviate some struggles
                     Organization          endured by patients with
                     Quality of Life       advanced heart failure.
                     measure

Stevens, Barlow,   Semi-structured         Peer mentors reflected
& Iliffe, 2014     interviews              positively on their
                                           experiences with the
                                           exercise program, which
                                           included meeting and
                                           befriending new people,
                                           seeing participants'
                                           progress, and receiving
                                           gratitude from
                                           participants. The
                                           relationship between peer
                                           mentors and participants
                                           seemed to be very
                                           important to the overall
                                           experience.

Bailey,            Semi-structured         The authors conceptualized
Gammage,           interview               positive body image as
van Ingen, &                               involving a core of body
Ditor, 2015                                acceptance, body
                                           appreciation/gratitude
                                           (appreciation/gratitude
                                           was considered a deeper
                                           layer of acceptance).
                                           Social support was
                                           considered facilitative
                                           for achieving these cores;
                                           gratitude was considered
                                           bi-directionally related
                                           to media literacy, a
                                           broader conceptualization
                                           of beauty, inner
                                           positivity, unconditional
                                           positive regard from
                                           others, and self-respect.

Citation                            Future Directions

Jones, Volker,     Future studies should examine training,
Vinajeras,         awareness, prevention, and interventions to
Butros,            be used for aiding this population. Young
Fitchpatrick, &    adults' history with cancer should continue to
Rossetto, 2010     be considered as they get older, and notable
                   aspects of their experience should be identified.
                   Future research should continue to explore how
                   ethnicity and age differentially impact cancer
                   survivors.

O'Sullivan &       Further study of quality of home life, the
Chard, 2010        effectiveness of follow-up services post-stroke,
                   and interventions to promote return to leisure
                   activities. More diverse samples, including post-
                   stroke stage, age, gender, and ethnicity, should
                   be employed. Future longitudinal research on
                   relevant interventions and support for this
                   population is merited.

Fries, Bowers,     Professional growth and commitment to
Gross, & Frost,    collaboration among students should continue to
2013               be studied across a variety of clinical
                   experiences. Greater immersion in another culture
                   or multiple experiences with such service-learning
                   opportunities should be subject to further
                   inquiry.

Kim, 2013          These findings should be compared to responses
                   from those of other cultures. More research
                   is needed on the impact and observations of
                   siblings in this population. Females should also
                   be examined in this context.

Rahmani &          None provided.
Brekke, 2013

Frye, 2014         Further studies should include participants
                   with multiple and additional types of cancer
                   and consider longitudinal methods, especially
                   when examining post-traumatic growth. Effects
                   of normal aging should be differentiated in
                   future studies, and the effects of community
                   support groups on post-traumatic growth for
                   cancer survivors should be investigated.

Huffman,           Patients with more diverse cardiac conditions
DuBois,            should be sampled to continue the examination
Mastromauro,       of positive psychological variables and their
Moore, Suarez,     impact on health. Examination of negative
& Park, 2014       psychological states, objective physical
                   health outcomes, and mixed methods (e.g.,
                   ecological momentary assessment) should
                   also be included in such studies.

Lambert D'raven,   These finding should be replicated in a larger
Moliver, &         sample and compared against a control group.
Thompson,          Reasons for drop-out of such a program should
2015               be explored, and the effect of medications
                   should be considered. Future research should
                   continue to bridge physical and mental health
                   domains.

O'Brien,           Future research should examine the effects
Donaghue,          of gratitude interventions post-transplant. A
Walker, &          larger sample with more diverse experiences
Wood, 2014         with transplants as well as their family
                   members and spouses are necessary for future
                   studies. The effect of gratitude should be
                   compared across other life-saving treatments.

Sacco, Park,       The relationship between gratitude and positive
Suresh, &          meaning and well-being should continue to be
Bliss, 2014        explored. If gratitude is induced, how is positive
                   meaning affected, and vice versa? Relationships
                   among psychosocial resources and well-being
                   outcomes merit further research.

Stevens, Barlow,   Study findings should be replicated in a larger
& Iliffe, 2014     and more diverse sample. Participants' homes
                   should be evaluated in order to determine the
                   best place to participate in the program and
                   receive mentorship. Peer mentor experiences
                   should continue to be studied to the effect of
                   improving such interventions.

Bailey,            A theory of positive body image should
Gammage,           continue to be investigated. A broader range
van Ingen, &       of functionality should be sampled in future
Ditor, 2015        research of body image and spinal cord injury.
                   Future inquiries should attempt to determine
                   directionality within this model and employ
                   mixed methods. Validation and use of positive
                   body image measures should be included in
                   future research in this area.

TABLE 3

Summary Table for 26 Quantitative Gratitude and Physical Health
Research (Including Health Behaviors and Mental Health)
from 2009 to 2015

                         Participants
Citation             (# female, mean age)         Method

Froh,               154 middle school         Correlational;
Yurkewicz, &        students (71; 12.14)      cross-sectional
Kashdan,
2009

Martinez-           105 Spanish               Experimental;
Marti, Avia, &      undergraduates            longitudinal
Hernandez-          (95; 20.70)
Lloreda, 2010

Rosmarin,           405 adults                Correlational;
Pirutinsky,         (not reported; not        cross-sectional
Cohen, Galler,      reported)
& Krumrei,
2011

Gavian, 2012        247 undergraduates        Experimental;
                    (173; not reported)       longitudinal

Osborne, Smith,     953 university faculty    Correlational;
& Huo, 2012         (484; 52.43) from four    cross-sectional
                    universities in
                    California

Plunkett, 2012      30 transplant             Correlational;
                    recipients (not           cross-sectional
                    reported; not reported)

Barraza, Grewal,    39 older adults           Experimental;
Ropacki, Perez,     (24; 80.33)               longitudinal
Gonzalez, &
Zak, 2013

Dijker, Nelissen,   435 secondary             Correlational;
& Stijnen, 2013     education students        cross-sectional
                    (244; 16.4) in the
                    Netherlands

Eaton, Bradley,     327 Australian adults     Correlational;
& Morrissey,        (256; 56) with one        cross-sectional
2013                of three chronic
                    illnesses (arthritis,
                    chronic obstructive
                    pulmonary disease
                    and diabetes)

Hill, Allemand,     962 Swiss adults (548;    Correlational;
& Roberts,          52.4)                     cross-sectional
2013

Monin, Levy, &      2025 U.S. veterans        Correlational;
Pietrzak, 2013      (72; 71.0) drawn          cross-sectional
                    from the National
                    Health and Resilience
                    in Veterans Study
                    sample

Ng& Wong,           224 Chinese chronic       Correlational;
2013                pain patients (127;       cross-sectional
                    45.66)

Pietrzak, Tsai,     2025 U.S. veterans        Correlational;
Kirwin, &           (63; 71.0) drawn          cross-sectional
Southwick,          from the National
2013                Health and Resilience
                    in Veterans Study
                    sample

Young &             110 pediatric patients    Descriptive;
Kemper, 2013        (69; 13) with pain        retrospective;
                                              cross-sectional

Kimmerling,         52 graduate and           Correlational;
2014                undergraduate             cross-sectional
                    students (41; 24.38)

Koenig, Berk,       129 somewhat              Correlational;
Daher, Pearce,      religious or spiritual    cross-sectional
Bellinger,          adults (90; 51.5)
Robins, Nelson,     with at least one
Shaw, Cohen, &      chronic medical
King, 2014          condition, a diagnosis
                    of major depressive
                    disorder with mild to
                    moderate symptoms

Lamke, Carlin,      20 nurses                 Quasi-
& Mason-            (not reported;            experimental;
Chadd, 2014         not reported)             longitudinal

Zahn, Garrido,      64 healthy adults         Quasi-
Moll, &             (31; 28.1)                experimental;
G raiman, 2014                                longitudinal

Knowlton,           258 adults                Correlational;
Mitchell,           (110; 47.6) in care       cross-sectional
Robinson,           for HIV who were
Nguyen,             former or current
Isenberg, &         injectors and their
Denison, 2015       258 informal
                    caregivers (153; 47.3)

Stoeckel,           136 undergraduates        Quasi-
Weissbrod, &        (19; 64) with either      experimental;
Ahrens, 2015        healthy, mentally         cross-sectional
                    ill, or physically ill
                    parents

Mental Health (not Physical Health)
but with Healthcare-Related Samples

Algoe &             54 women diagnosed        Correlational;
Stanton, 2012       with metastatic breast    longitudinal
                    cancer (54; 56.97)

Azuri & Tabak,      135 donor family          Correlational;
2012                members and organ         cross-sectional
                    recipients in Israel
                    (62; 50)

Tsui, 2012          102 adult health care     Experimental;
                    professionals             longitudinal
                    (56; not reported)
                    in Hong Kong

Cheng, Tsui, &      102 adult health care     Experimental;
Lam, 2015           professionals (56; not    longitudinal
                    reported) in Hong
                    Kong

Krause,             1774 adults               Correlational;
Emmons, &           (1100; 53.1) from a       cross-sectional
Ironson, 2015       nationwide survey
                    who attend church
                    at least three times
                    per year

Mills, Redwine,     186 adults                Correlational;
Wilson, Pung,       (9; 66.4) with            cross-sectional
Chinh,              Stage B asymptomatic
Greenberg,          heart failure
Lunde, Maisel,
& Raisinghani,
2015

Citation                                 Measures

Froh,               * Gratitude Adjective Checklist (GAC)
Yurkewicz, &        * 22 items assessing positive and negative
Kashdan,              affect
2009                * 2 items assessing life satisfaction
                    * Brief Multidimensional Students' Life
                      Satisfaction Scale (BMSLSS)
                    * 2 items assessing gratitude in response
                      to aid
                    * Physical symptom checklist
                    * 2 items assessing prosocial behavior
                    * 2 items assessing social support

Martinez-           * 3 items assessing state gratitude
Marti, Avia, &      * 30 items assessing affect
Hernandez-          * 2 items assessing global appraisals of
Lloreda, 2010         well-being
                    * 13 items assessing physical symptoms
                    * Number of pain relievers used that
                      day
                    * 4 items assessing sleep quality
                    * 4 items assessing quality of relationship
                      with significant other
                    * 1 item assessing sensitivity to others'
                      needs
                    * GQ-6 (Spanish version)
                    * Other report of global subjective well-
                      being, gratitude, and sensitivity to
                      others (follow-up only)

Rosmarin,           * GQ-6
Pirutinsky,         * Religious Gratitude Questionnaire
Cohen, Galler,        (RGQ)
& Krumrei,          * 5 items assessing multidenominational
2011                  religious commitment
                    * Subjective Happiness Scale (SHS)
                    * SWLS
                    * Positive and Negative Affect Schedule
                      (PANAS)
                    * Short-Form Health Survey (SF-12)

Gavian, 2012        Measures of: life satisfaction, serenity,
                    relaxation, positive affect, perceived
                    control, negative affect (i.e., depression,
                    anxiety, stress), and health indicators
                    (i.e., physical symptoms)

Osborne, Smith,     * 2 items assessing individual relative
& Huo, 2012           deprivation
                    * 5 items assessing discrete emotions
                    * 9 items assessing pursuit of voice
                    * 3 items assessing pursuit of exit
                    * 4 items assessing pursuit of neglect
                    * 3 items assessing loyalty
                    * 2 items assessing physical health
                    * 5 items assessing mental health
                    * 1 item assessing optimism about the
                      situation
                    * 1 item assessing the responsibility of
                      the university
                    * 4 items assessing strength of
                      identification with university

Plunkett, 2012      10 items assessing which learning
                    activities were most effective during
                    rehabilitation and was/were the
                    source(s) of critical information

Barraza, Grewal,    * Profile of Mood States (POMS)
Ropacki, Perez,     * Items assessing daily engagement in social
Gonzalez, &           activities
Zak, 2013           * Systolic blood pressure (SBP)
                    * Diastolic blood pressure (DBP)
                    * GQ-6
                    * SWLS
                    * Affect Intensity Measure (AIM)
                    * Religious Commitment Inventory (RCI)
                    * Mini-Mental State Examination (MMSE)
                    * Modified Mini-Mental State
                      Examination (3MS)
                    * Geriatric Depression Scale (GDS)
                    * SF-36
                    * Items assessing giving, donations, and
                      volunteering

Dijker, Nelissen,   * 3-item Fear scale from a previous study
& Stijnen, 2013     * 3-item Anger scale from a previous study
                    * 2-item Pity scale from a previous study
                    * 3-item Positive Self-Feelings scale from
                      a previous study
                    * Single-item measure of gratitude
                    * Single-item measure of guilt
                    * 5-item measure of intent to become an
                      organ donor
                    * Actual donor registration status

Eaton, Bradley,     * GQ-6
& Morrissey,        * Rye Forgiveness Scale (RFS)
2013                * PANAS
                    * World Health Organization Health
                      Quality of Life Scale--Brief
                    * SWLS
                    * Ten-Item Personality Inventory
                    * Marlowe-Crowne Social Desirability
                      Scale

Hill, Allemand,     * GQ-6
& Roberts,          * Short-Form Health Survey (SF-12)
2013                * 5 items assessing healthy activities
                    * 5 items assessing willingness to seek help
                      for health concerns
                    * Big Five Inventory (BF1)

Monin, Levy, &      * 1 item assessing combat exposure
Pietrzak, 2013      * Number of medical conditions endorsed
                    * Somatization subscale of Brief Symptom
                      Inventory--18
                    * Patient Health Questionnaire-
                      4 (PHQ-4)
                    * Posttraumatic Stress Disorder Checklist
                    * Medical Outcomes Study Cognitive
                      Functioning Scale--Revised
                    * Connor-Davidson Resilience Scale
                    * Purpose in Life Scale--Short Form
                    * GQ-6
                    * Subjective Happiness Scale
                    * 1 item from Life Orientation Test -
                      Revised
                    * 1 item assessing social support
                    * 1 item assessing attachment style
                    * 5-item version of Medical Outcomes
                      Study social support survey
                    * 3 items assessing caregiving status
                    * 2 items assessing physical and emotional
                      strain
                    * 1 item assessing feelings of reward from
                      caregiving

Ng& Wong,           * Chronic Pain Grade Questionnaire
2013                  (CPG)
                    * Hospital Anxiety and Depression Scale
                      (HADS)
                    * GQ-6
                    * Pittsburgh Sleep Quality Index
                      (PSQI)

Pietrzak, Tsai,     * 1 item assessing successful aging
Kirwin, &           * SF-8 Health Survey
Southwick,          * Quality of Life Enjoyment and
2013                  Satisfaction Questionnaire--Short Form
                    * Medical Outcomes Study Cognitive
                      Functioning Scale--Revised
                    * Number of medical conditions endorsed
                    * Somatization subscale from Brief
                      Symptom Inventory--18
                    * 2 items assessing disability
                    * Trauma history screen
                    * MINI Neuropsychiatrie Interview
                    * PTSD Checklist
                    * Fagerstrom Test for Nicotine
                      Dependence
                    * Patient Health Questionnaire (PHQ-4)
                    * Duke University Religion Index
                    * Connor-Davidson Resilience Scale
                    * Purpose in Life I est--Short Form
                    * 1 item assessing community integration
                    * 1 item from Life Orientation Test -
                      Revised
                    * 1 item from Curiosity and Exploration
                      Inventory--II
                    * 1 item assessing social support
                    * 1 item assessing attachment style
                    * 2 items assessing social engagement
                    * 4 items assessing active lifestyle
                    * 2 items assessing altruism
                    * BMI
                    * 1 item assessing smoking status
                    * Ten-Item Personality Inventory
                    * 3 items from Expectations Regarding
                      Aging Survey
                    * 1 item assessing impact of military on life

Young &             Intake forms and physician records
Kemper, 2013

Kimmerling,         * Gratitude Adjective Checklist
2014                * The Gratitude Resentment and
                      Appreciation Test (GRAT) Short Form
                    * GQ-6
                    * Blood pressure
                    * Resting heart rate
                    * Body mass index
                    * Self-report physical symptoms checklist
                    * BFI
                    * The Life Orientation Test--Revised
                    * 2 items assessing alcohol consumption
                    * 1 item assessing frequency of exercise
                    * 2 items assessing frequency and quantity
                      of tobacco use

Koenig, Berk,       * Duke Activity Status Index (DASI)
Daher, Pearce,      * Cumulative Illness Rating Scale
Bellinger,            (CIRS)
Robins, Nelson,     * Charlson Comorbidity Index (CCI)
Shaw, Cohen, &      * Brief Mini-Mental State Exam
King, 2014          * Mini-International Neuropsychiatrie
                      Interview (MINI)
                    * Beck Depression Inventory (BDI-II)
                    * Purpose in Life (PlL) l est
                    * Life Orientation Test--Revised
                      (LOT-R)
                    * Interpersonal Generosity Scale (IGS)
                    * GQ-6
                    * 5 items assessing multiple domains of
                      religious involvement
                    * Daily Spiritual Experiences Scale (DSES)
                    * Intrinsic Religiosity (IR) scale
                    * Brief RCOPE (BRCOPE)
                    * Buddhist COPE (BCOPE)
                    * Social interaction and subjective
                      support subscales of the Duke Social
                      Support Index (DSSI)
                    * Marital status

Lamke, Carlin,      * Personal and Organizational Quality
& Mason-              Assessment-Revised
Chadd, 2014         * Coates Caring Efficacy Scale

Zahn, Garrido,      * EMRI
Moll, &             * Selection of one of the following
G raiman, 2014        emotion words in response to the
                      prompt: pride, gratitude, embarrassment,
                      guilt, indignation/anger, and
                      none/other
                    * Rating of strength of the above selected
                      feeling
                    * Rosenberg Self-Esteem Scale
                    * PANAS

Knowlton,           * Single-item measure assessing 7-day
Mitchell,             treatment adherence
Robinson,           * Roche Cobas Amplicor for assessing
Nguyen,               viral loading
Isenberg, &         * Items assessing current substance use,
Denison, 2015         depressive symptoms, and physical
                      limitations (Latkin et al., 2004; Lawton
                      & Brody, 1967; Pearlin et al., 1990)
                    * Items assessing participants' length
                      of time in treatment; caregiver's HIV
                      seropositive status; and caregiver's
                      reports of past closeness with someone
                      who died of AIDS
                    * Items assessing role of caregiver (family
                      or friend)
                    * Items assessing relationship reciprocity
                      variables (e.g., caring, affection; Horwitz,
                      1993; Pearlin et al., 1990)
                    * Single item assessing fear of caregiving

Stoeckel,           * Demographics and Parental Health
Weissbrod, &          Information Questionnaire
Ahrens, 2015        * GQ-6
                    * GRAT
                    * PANAS
                    * CES-D
                    * Family Quality of Life Scale (FQOL)
                    * BAI

Mental Health (not Physical Health)
but with Healthcare-Related Samples

Algoe &             * 2 items to assess perception of the
Stanton, 2012         benefactor's thoughts about the recipient
                    * 2 items to assess ego transcendence
                    * Several items to assess their emotional
                      response to a particular situation when
                      someone did something for them
                    * Items assessing degree and frequency of
                      14 emotions
                    * 3 items to assess gratitude
                    * 3 items to assess anger
                    * Items to assess social support
                    * Items to assess perceived social support

Azuri & Tabak,      32 items assessing how participants
2012                perceived the role of the transplant
                    coordinator in establishing contact
                    between the parties; the benefits and
                    disbenefits of the contact/non-contact for
                    themselves and their level of satisfaction
                    with the contact/non-contact

Tsui, 2012          * Perceived Stress Scale (PSS)
                    * Chinese Affect Scale (CAS)
                    * SWLS
                    * CES-D

Cheng, Tsui, &      * CES-D
Lam, 2015           * PSS

Krause,             * 10-item checklist of physical symptoms
Emmons, &             (Magaziner et al., 1996)
Ironson, 2015       * 2 items assessing overall self-reported
                      physical health
                    * Single item assessing church attendance
                      (Fetzer Institiute/National Institute on
                      Aging Working Group, 1999)
                    * 3 items assessing spiritual support from
                      fellow congregants (Krause, 2008)
                    * 3 items assessing God image (Ironson
                      et al., 2011)
                    * 3 items assessing gratitude to God
                      (Rosmarin et al., 2011)
                    * 4 items assessing hope (Krause, 2002;
                      Scheier & Carver, 1985)

Mills, Redwine,     * GQ-6
Wilson, Pung,       * The Functional Assessment of Chronic
Chinh,                Illness Therapy Spiritual
Greenberg,          * Well-Being Scale (FACIT-SP12)
Lunde, Maisel,      * BDI-IA
& Raisinghani,      * PSQI
2015                * Multidimensional Fatigue Symptom
                      Inventory-Short Form (MFSI)
                    * Cardiac Self-Efficacy Questionnaire
                      (CSEQ)
                    * Circulating levels of nflammatory
                      markers CRP, TNF- , IL-6, IFN-gamma
                      & ST2 determined using ELISA

Citation                               Conclusions

Froh,               Positive associations were found between
Yurkewicz, &        gratitude and positive affect, global and domain
Kashdan,            specific life satisfaction, optimism, social
2009                support, and prosocial behavior; most relations
                    remained even after controlling for positive
                    affect. Gratitude demonstrated a negative
                    relation with physical symptoms, but not with
                    negative affect. Relational fulfillment mediated
                    the relation between gratitude and physical
                    symptoms. The relation between gratitude and
                    family support was moderated by gender,
                    indicating that boys, compared with girls, appear
                    to derive more social benefits from gratitude.
                    Girls tended to report more gratitude than boys,
                    but boys showed a stronger relation between
                    gratitude and a single positive outcome.

Martinez-           Participants completed a 2-week intervention of
Marti, Avia, &      either writing down five things they were
Hernandez-          grateful for each day, writing down five daily
Lloreda, 2010       hassles, or writing down any five things that
                    have affected the participant that day. Findings
                    for Emmons and McCullough (2003) were replicated
                    in this Spanish sample in that state gratitude
                    and positive affect were significantly greater in
                    the gratitude condition than the hassles
                    condition at post-test. However, positive affect
                    seemed to mediate the effect of the gratitude
                    intervention just as much as gratitude did, and
                    differences in gratitude and positive affect
                    among conditions were not maintained at follow-
                    up. No differences were found between the
                    conditions in measures of physical well-being.

Rosmarin,           Gratitude was positively correlated with religious
Pirutinsky,         commitment. This relationship was fully medi-
Cohen, Galler,      ated by gratitude towards God. The interaction
& Krumrei,          of religious commitment and religious gratitude
2011                added unique variance in predicting mental

                    well-being, over and above general gratitude. This
                    suggests that being grateful to God enhances the
                    psychological benefits of gratitude in accordance
                    with one's level of religious commitment.

Gavian, 2012        Results indicated that progressive muscle
                    relaxation (PMR) is an effective intervention. At
                    post-intervention, those in the PMR condition
                    reported significantly more perceived control
                    and serenity than both the gratitude and control
                    groups. Those in the PMR group also had
                    significantly lower negative affect than the
                    control group. Group differences in stress and
                    physical health symptom ratings, although
                    marginally significant, revealed results again in
                    favor of PMR. At follow-up (30 days later) the
                    PMR group maintained significantly lower negative
                    affect than the control group. There were no
                    effects of the gratitude intervention on any
                    outcomes nor were there group differences in
                    stress reactivity.

Osborne, Smith,     Gratitude mediated the relationship between
& Huo, 2012         individual relative deprivation and loyalty in
                    response to university furloughs. Anger, fear,
                    and sadness were also related to individual
                    relative deprivation, and self-reported physical
                    and mental health was negatively correlated with
                    individual relative deprivation. These results
                    demonstrate the interaction between emotions and
                    individual relative deprivation that can be
                    useful in well-being of employees and
                    organizational issues.

Plunkett, 2012      Experiences of achieving post organ transplant
                    success were classified into six categories: (1)
                    physical activity, (2) gratitude, (3) education,
                    (4) personal accountability, (5) confidence/
                    empowerment, and (6) the significance of life.
                    The results confirmed presence of adult learning
                    assumptions found in Knowles's theory of
                    andragogy and leadership attributes among the
                    study participants.

Barraza, Grewal,    Participants received 40 IU intranasal oxytocin
Ropacki, Perez,     or placebo for 10 days. Mood and cardiovascular
Gonzalez, &         state did not change in either condition;
Zak, 2013           however, oxytocin seemed to increase trait
                    gratitude and buffer declines in gratitude,
                    physical functioning and fatigue experienced by
                    the control group. Oxytocin appeared to have a
                    mild but safe effect on older adults.

Dijker, Nelissen,   Those who do not donate organs tend to arouse
& Stijnen, 2013     fear, anger, and guilt in others, while
                    themselves feeling pity or sympathy, especially
                    when the other person in the scenario could
                    donate. Guilt was pervasive in these
                    participants, regardless of the other person's
                    status. Participants felt grateful when they were
                    able to donate organs. Overall, people can be
                    sensitive to others' needs and still ignore them,
                    suggesting that altruism and self-preservation
                    can co-exist independently.

Eaton, Bradley,     Gratitude, and to a lesser extent forgiveness,
& Morrissey,        was related to enhanced quality of life, with
2013                most effects mediated by increased positive
                    affect. Findings support the Broaden and Build
                    theory as a mechanism of gratitude and
                    forgiveness' relationship with quality of life.
                    Quality of life may be better enhanced by
                    gratitude interventions than forgiveness
                    interventions.

Hill, Allemand,     Dispositional gratitude correlated positively
& Roberts,          with self-reported physical health, and this link
2013                was mediated by psychological health, healthy
                    activities, and willingness to seek help for
                    health concerns. However, the indirect effects
                    for psychological health and healthy activities
                    were stronger for older than younger adults. In
                    other words, the mechanisms explaining why
                    gratitude predicts health appear to differ across
                    adulthood.

Monin, Levy, &      Veteran caregivers (20.4% of the sample)
Pietrzak, 2013      experienced less emotional strain with more
                    combat exposure, and grandparenting was
                    experienced as particularly rewarding. Physical
                    strain was negatively associated with resilience;
                    emotional strain was positively associated with
                    depressive symptoms; gratitude, happiness,
                    and social support were associated with greater
                    feelings of reward.

Ng& Wong,           Insomnia correlated positively with chronic pain
2013                symptoms. Higher gratitude was associated with
                    better sleep and lower depression. Gratitude
                    affected depression more directly, but sleep was
                    a stronger mediator for gratitude's relationship
                    with anxiety, such that when controlling for
                    sleep, the correlation between gratitude and
                    anxiety was nonsignificant. In general, chronic
                    pain patients in this study who reported better
                    sleep had less depression and anxiety, and better
                    sleep was associated with higher gratitude.

Pietrzak, Tsai,     82.1% of veterans rated themselves as aging
Kirwin, &           successfully, a combination of self-rated
Southwick,          successful aging, quality of life, and physical,
2013                mental, cognitive, and social functioning.
                    Physical health difficulties and current
                    psychological distress were most strongly
                    negatively related to scores on this composite of
                    successful aging. Resilience, gratitude, purpose
                    in life, and community integration were most
                    strongly positively related to successful aging,
                    perhaps demonstrating their protective value.
                    These factors may be related to successful aging
                    via ability to cope with stress and transitions
                    and promoting meaning in life.

Young &             Pediatric pain patients reported a myriad of
Kemper, 2013        health concerns related to their pain. Many
                    families wished to have counseling about diet and
                    nutrition, exercise, sleep, and stress
                    management. Among stress-reducing techniques
                    recommended to patients were: biofeedback,
                    gratitude journals, and yoga. This integrated
                    style of care may be helpful for positive health
                    outcomes. If pain is not managed, it can lead to
                    risk for developing addiction and other attempts
                    at coping.

Kimmerling,         The relationship between gratitude and physical
2014                health outcomes was suppressed by optimism
                    and Big Five personality factors. When these
                    were controlled, gratitude was negatively
                    correlated with diastolic blood pressure.
                    Gratitude was uncorrelated with exercise
                    frequency, tobacco use, and alcohol use.

Koenig, Berk,       Religious measures were not related to depressive
Daher, Pearce,      symptoms, and it did not buffer the impact
Bellinger,          of physical disability on depression. Religious
Robins, Nelson,     measures were related to higher meaning and
Shaw, Cohen, &      purpose in life, optimism, generosity toward
King, 2014          others, and gratitude, all of which had a strong
                    negative relationship with depressive symptoms in
                    this depressed sample.

Lamke, Carlin,      Participants received three 2-hour Jin Shin
& Mason-            Jyutsu * self-care training sessions and agreed
Chadd, 2014         to practice self-care daily over a 30-day period.
                    Participants reported significant increases in
                    positive outlook, gratitude, motivation,
                    calmness, and communication effectiveness at
                    post-test. They significantly decreased in anger,
                    resentfulness, depression, stress symptoms, time
                    pressure, morale issues, muscle aches,
                    sleeplessness, and headaches. Participants also
                    experienced statistically significant increases
                    in multiple domains of caring efficacy for their
                    patients.

Zahn, Garrido,      Four conditions of stimuli were presented to each
Moll, &             participant to induce positive self-agency (e.g.,
G raiman, 2014      you are being nice to your best friend), positive
                    other-agency (e.g., your best friend is being
                    nice to you), negative self-agency, or negative
                    other-agency. Those with smaller cuneus and
                    precuneus grey matter volumes experienced pride
                    more readily; those with larger right inferior
                    temporal volume of grey matter experienced
                    gratitude more readily. Subgenual cingulate grey
                    matter volume in the left superior temporal
                    sulcus and anterior dorsolateral prefrontal
                    cortices was negatively correlated with proneness
                    to guilt or indignation. Thus, these moral
                    sentiments involve grey matter volume differences
                    in different areas of the brain.

Knowlton,           High concordance between caregiver report of
Mitchell,           treatment adherence and actual viral suppression
Robinson,           was associated with communication of affection
Nguyen,             and gratitude among dyads, as well as age, better
Isenberg, &         physical functioning, caregiver having been close
Denison, 2015       to someone who died of AIDS in the past, and fear
                    of caregiving. Thus, in dyads with more affective
                    and grateful communication, caregiver knowledge
                    of treatment adherence was more accurate.
                    Furthermore, participants' physical limitations
                    were associated with low concordance between
                    caregiver report and viral suppression.

Stoeckel,           Dispositional gratitude was associated with lower
Weissbrod, &        depression, lower anxiety, and higher family
Ahrens, 2015        quality of life. Dispositional gratitude
                    significantly moderated (buffered) the
                    relationship between parental health status and
                    participant depression and anxiety, even when the
                    onset of the parent's illness was chronic (as
                    opposed to acute). This is consistent with
                    research which supports gratitude as a buffer for
                    internalizing symptoms.

Mental Health (not Physical Health)
but with Healthcare-Related Samples

Algoe &             Gratitude was defined as an other-focused
Stanton, 2012       positive emotion that functions to promote
                    high-quality relationships. One set of analyses
                    provide support for the hypothesized role of
                    ego-transcendence in feeling gratitude upon
                    receipt of a benefit from another person. As
                    predicted, grateful responding to received
                    benefits predicted an increase in perceived
                    social support over 3 months only for women low
                    in ambivalence over emotional expression.

Azuri & Tabak,      Far more 'contacters' than 'non-contacters'
2012                wanted the transplant coordinator to take an
                    active role in establishing contact. No less than
                    60% of non-contacters wanted contact in the
                    future, and 50% were dissatisfied with the
                    absence of contact. Both donor families and organ
                    recipients would respond positively to the
                    coordinator taking the initiative in establishing
                    mutual contact.

Tsui, 2012          After random assignment to a gratitude, hassles,
                    or control condition, participants' psychological
                    well-being was positively associated with the
                    gratitude group, especially in perceived stress,
                    life satisfaction and positive affect at the
                    third time point. Evidence of marginal effects
                    from depression at the second time point was
                    reported in the hassle group as well. This
                    implies that positive thinking of gratitude can
                    be a way for relieving their stress.

Cheng, Tsui, &      After random assignment to a gratitude, hassles,
Lam, 2015           or control condition, participants in the
                    gratitude condition experienced a decrease in
                    perceived stress and depressive symptoms at
                    post-test and at 3-month follow-up; the rate of
                    decline slowed over time. Neither the hassles nor
                    the control condition reported significant
                    changes in perceived stress or depressive
                    symptoms; however, participants in the gratitude
                    condition had more years of experience, which was
                    related to a lower baseline rate of stress.
                    Overall, being reminded of and grateful for
                    positive events in one's stressful day-to-day
                    routine may be helpful for mitigating stress and
                    depressive symptoms.

Krause,             Those with higher attendance at worship services
Emmons, &           tend to have more benevolent images of God,
Ironson, 2015       via receiving more spiritual support from other
                    congregants. Those with more benevolent
                    images of God feel more gratitude toward God;
                    greater gratitude to God was associated with
                    hope for the future, which was associated with
                    better self-rated health and fewer physical
                    health symptoms. Despite its role as a mechanism
                    in these relationships, spiritual support alone
                    was associated with more physical symptoms; this
                    is inconsistent with previous literature.

Mills, Redwine,     Spiritual well-being and gratitude were
Wilson, Pung,       associated with better sleep, fewer depressive
Chinh,              symptoms, less fatigue, and better self-efficacy
Greenberg,          for self-care related to cardiac functioning.
Lunde, Maisel,      Gratitude was also associated with fewer
& Raisinghani,      inflammatory biomarkers. Gratitude fully mediated
2015                spiritual well-being's relationships with sleep
                    quality and depression. Gratitude partially
                    mediated spiritual well-being's relationships
                    with fatigue and self-efficacy.

Citation                            Future Directions

Froh,               Future research should teach grateful
Yurkewicz, &        attributions in interventions. Gratitude
Kashdan,            should be examined with hope and forgiveness
2009                in the context of the broaden-and-build
                    theory. Experimental and longitudinal studies
                    are needed to demonstrate how adolescents
                    develop in this way. Does family support cause
                    gratitude, or is it a result?

Martinez-           Gratitude measures that translate to the
Marti, Avia, &      Spanish language more accurately are needed.
Hernandez-          Future studies should include a more neutral
Lloreda, 2010       control condition. Additional mediators in
                    gratitude interventions should be examined,
                    in addition to personality characteristics and
                    trait mood.

Rosmarin,           Experimental research and more diverse
Pirutinsky,         religious representation is needed in this area.
Cohen, Galler,      Does religious gratitude add to well-being over
& Krumrei,          and above general gratitude?
2011

Gavian, 2012        Buffering stress and improving mental health
                    via positive psychology should continue to be
                    explored.

Osborne, Smith,     Future research should examine the
& Huo, 2012         circumstances under which a furlough
                    might be perceived positively by employees.
                    Other-report and behavioral studies, as well
                    as longitudinal methods, should be employed
                    in this area. Responses to individual relative
                    deprivation should continue to be studied.

Plunkett, 2012      Information about the preferred learning
                    activities and the barriers to overcome for a
                    more effective post-transplant rehabilitation
                    process should be put into practice.

Barraza, Grewal,    Future studies should seek to generalize these
Ropacki, Perez,     findings in other populations and sample sizes.
Gonzalez, &         Effects of varying doses of oxytocin as well as
Zak, 2013           other hormones and their impact on mental
                    and physical well-being should continue to be
                    studied.

Dijker, Nelissen,   Generalizability of results should be examined
& Stijnen, 2013     among different populations. Antecedents to
                    these emotions should examined. Emotions
                    related to willingness to donate organs should
                    continue to be explored.

Eaton, Bradley,     Results should be replicated in a larger
& Morrissey,        and more diverse sample. Experimental
2013                methodology and less reliance on self-report
                    measures should be employed in future studies.
                    Positive psychology interventions should
                    continue to be studied in the chronically ill.

Hill, Allemand,     Longitudinal methods should be used to
& Roberts,          validate this research. Valid, reliable, and
2013                objective health measures should also be used.

Monin, Levy, &      Further research should examine factors
Pietrzak, 2013      related to minority veteran caregivers' greater
                    perception of strain than minority non-
                    veteran caregivers. Type of health conditions
                    that led veterans to caregiving roles, as well
                    as the number and nature of their caregiving
                    roles, should be explored in future studies.
                    Longitudinal data is needed to further examine
                    the relationship between caregiving and health.
                    Mechanisms therein may be illuminated by
                    assessment of caregiver needs, posttraumatic
                    growth, and generativity.

Ng& Wong,           Gratitude interventions should be examined
2013                in the chronic pain population, since
                    psychological distress hinders the progress
                    of chronic pain treatment. Longitudinal
                    studies should examine the effect of sleep and
                    gratitude on chronic pain and psychological
                    distress in multiple cultures.

Pietrzak, Tsai,     Future research should evaluate positive
Kirwin, &           psychological interventions for gratitude,
Southwick,          purpose in life, and community integration,
2013                especially in reference to successful aging.
                    Both quantitative and qualitative methods
                    should be employed to explore more deeply
                    military-specific life changes as they relate to
                    successful aging, particularly in a variety of
                    subsets of veterans who may differ in this way.
                    Longitudinal methods and objective, validated
                    measurements should be considered in future
                    inquiries, and more diverse samples should be
                    recruited. Replication of the current findings
                    is warranted, as well as future explorations
                    of other related factors, such as genetics,
                    neurobiologie factors, nutrition, wisdom, etc.

Young &             Differential effects for the variety of
Kemper, 2013        alternative therapies suggested should be studied
                    further. Future research should also
                    longitudinally examine the effects of pain
                    management on substance use and addiction. Cost
                    and impact of these programs should continue to
                    be assessed in order for patients to achieve the
                    best treatment. Larger scale studies should
                    examine the diversity within chronic pain
                    populations and with larger sample sizes.

Kimmerling,         Objective measures of physical health should
2014                continue to be studied in their relation to
                    gratitude. The relationship between gratitude
                    and diastolic blood pressure in particular
                    should be further examined.

Koenig, Berk,       Further investigation of causal relationships
Daher, Pearce,      among these variables is warranted.
Bellinger,
Robins, Nelson,
Shaw, Cohen, &
King, 2014

Lamke, Carlin,      Future research should consider the
& Mason-            implementation of Jin Shin Jyutsu * for more
Chadd, 2014         nurses in their work environment.

Zahn, Garrido,      Similar studies should be conducted on
Moll, &             participants with Alzheimer's disease and
G raiman, 2014      post-cortical atrophy to confirm post-cortical
                    networks' roles in moral behaviors.

Knowlton,           Future research should examine patients
Mitchell,           enrolled in a broader variety of treatment types.
Robinson,           Longitudinal data is needed for research on
Nguyen,             HIV patients and positive outcomes associated
Isenberg, &         with healthy caregiving relationships. Future
Denison, 2015       studies should offer measures of caregiver
                    relationship to the patient in addition to the
                    caregiver.

Stoeckel,           Further research should examine whether
Weissbrod, &        confounding variables, such as resilience,
Ahrens, 2015        explain why gratitude moderates the
                    relationship between parental health status
                    and children's mental health variables.
                    Multiple measures of gratitude should
                    continue to be used. Experimental and
                    longitudinal inquiries and more diversely-aged
                    samples in this area are needed.

Mental Health (not Physical Health)
but with Healthcare-Related Samples

Algoe &             The chronically stressful context is an
Stanton, 2012       important testing ground for theory on
                    gratitude and other positive emotions. Men
                    should also be examined for these findings.

Azuri & Tabak,      Future studies should explore developing
2012                the role of the transplant team and how it
                    influences the families and recipients. Cultural
                    generalizability for these findings should be
                    established.

Tsui, 2012          Gratitude interventions for this population
                    should continue to be explored.

Cheng, Tsui, &      Future research should consider the dose-
Lam, 2015           response relation for gratitude interventions.
                    Future studies of gratitude interventions
                    should include longer follow-up, larger
                    samples, and a more diverse array of health care
                    providers. The role of collegial relationships
                    on the relationship between gratitude and
                    mental health should be examined. Additional
                    outcome measures, including job productivity
                    and quality of patient care, should be included
                    in future studies.

Krause,             This model should continue to be evaluated
Emmons, &           with the addition of stress and coping as a
Ironson, 2015       mechanism between gratitude and hope.
                    Longitudinal research is needed to determine
                    directionality of these relationships.

Mills, Redwine,     More studies and dissemination of gratitude
Wilson, Pung,       interventions for cardiac populations is
Chinh,              merited.
Greenberg,
Lunde, Maisel,
& Raisinghani,
2015