MUSIC SHIFTS FRONTAL EEG IN DEPRESSED ADOLESCENTS.

Field, Tiffany ; Martinez, Alex ; Nawrocki, Thomas 等

ABSTRACT

Recent studies have found that positive affect is associated with greater relative left frontal EEG activation and negative affect is associated with greater relative right frontal EEG activation. Further, chronically depressed adults typically display stable right frontal EEG activation. The present study investigated the effects of music on mood state and right frontal EEG activation associated with chronic depression. Fourteen chronically depressed female adolescents listened to rock music for a 23-minute session. These adolescents were compared with a control sample of chronically depressed female adolescents who were simply asked to sit and relax their minds and their muscles for the same time period. EEG was recorded during baseline, music, and post-music for three minutes each, and saliva samples were collected before and after the session to determine the effects of the music on stress hormone (cortisol) levels. No group differences or changes were noted for observed or reported mood state. However, cortisol levels decreased and relative right frontal activation was significantly attenuated during and after the music procedure. It was concluded that music had positive effects on the physiological and biochemical measures even though observed and self-reported mood did not change.

Music reduces stress (Stratton, 1992) and anxiety levels (Mornhinweg, 1992), and even enhances performance on abstract/spatial reasoning tests (Rauscher, Shaw, & Ky, 1993). According to some researchers, these effects can be attributed to music's ability to alter mood states (Mornhinweg, 1992). Music has improved mood according to self-report (Kenealy, 1988), and heart rate and systolic blood pressure have also been shown to improve (Pignatello, Camp, Elder, Thomas, & Rasar, 1989). In addition, music techniques have altered behavior in depressed individuals (Hanser, 1990; Williams & Dorrow, 1983). The question for this study was whether music could alter electrophysiological and biochemical measures of depression, namely right frontal EEG activation and stress hormone (cortisol) levels.

Recent studies suggest that affective states are associated with EEG patterns in the frontal region of the brain (Fox, 1991; Fox & Davidson, 1987). Specifically, left frontal asymmetry has been associated with positive affect (approach emotions) or decreased negative affect, whereas right frontal asymmetry has been associated with negative affect (withdrawal emotions) or decreased positive affect (Ahern & Schwartz, 1985; Davidson, Ekman, Saron, Senulis, & Friesen, 1990). In addition, chronically depressed adults are noted to have right frontal activation even during remission of depressed behavior symptoms (Henriques & Davidson, 1990). Elevated cortisol has also been associated with depression, and relaxation interventions have been noted to decrease cortisol levels in depressed adolescents (Field, Morrow, Valdeon, Larson, Kuhn, & Schanberg, 1992).

The present study differed from previous research in that it assessed the effects of music on chronically depressed adolescents, particularly the effects on their right frontal EEG activation and their cortisol levels. Improved mood was expected to be accompanied by shifts in frontal EEG asymmetry, from relative right frontal EEG activation to relative left frontal EEG activation, and by decreases in salivary cortisol levels.

METHOD

Sample

Chronically depressed adolescent females (N = 28) were recruited from an adolescent clinic based on their Beck Depression Inventory (BDI) scores and Diagnostic Interview Schedule (DIS) diagnoses (adolescents receiving medication were excluded). The BDI (Beck, Ward, Mendelson, Mach, & Erbaugh, 1961) has 21 items, scored on a four-point scale, indicating the presence/absence and severity of depressed feelings/behaviors/symptoms. The DIS is a standardized diagnostic interview that addresses specific symptoms as well as their chronology, duration, and associated impairments. It has a step structure that minimizes interviewing time. Answers are coded 0 (corresponding to no), 1 (somewhat or sometimes), and 2 (yes). Reliability and validity of the DIS have been found to be as good as or better than other structured diagnostic interviews (Costello, Edelbrock, & Costello, 1985). The interviews were conducted by one interviewer who had received training at a national DIS training workshop. For this study, only the Aff ective Disorder Module was used to assess depression.

The adolescent females in this study received a DIS diagnosis of dysthymia (not major depression disorder) with recurrent episodes, and all scored above 16 (the typical cutoff used in depression research) on the BDI (mean = 28.9). They were single, ranged in age from 14 to 19 years (mean = 16.8), and were African American (65%) or Hispanic (35%) and low socioeconomic status (Hollingshead mean = 4.4). They were randomly assigned to a music group or a control group that was simply asked to relax their minds and their muscles for the same time period that the experimental group listened to music.

Measures

Behavior Observation Scale (BOS) (Field, Morrow, Valdeon, Larson, Kuhn, & Schanberg, 1992). The females were videotaped for 20 minutes before, during, and after the sessions. They knew they were being videotaped, but presumably any videotaping effects, such as increasing positive affect, would affect all three segments and both groups. The videotaped behaviors were rated on the Behavior Observation Scale by two independent raters who were trained to .90 reliability by a rater who had conducted BOS observations in two previous studies, one providing relaxation therapy for depressed adolescent psychiatric patients (Platania-Solazzo, Field, Blank, Seligman, Kuhn, Schanberg, & Saab, 1992) and the other providing massage therapy for the same types of adolescents (Field et al., 1992). The BOS rates subjects' state, affect, activity level, vocalizations, anxiety, cooperation, and fidgeting/nervous behavior on a three-point scale (low, moderate, high). Interobserver reliabilities based on

Kappa coefficients ranged f rom .72 to .87 (mean = .77).

Depression Adjective Checklist (DACL). The DACL is a 32-item adjective checklist describing mood states. It has been used with adolescent samples and has good psychometric properties. The DACL was administered before and after the music and control sessions.

Salivary Cortisol. Salivary cortisol samples were collected prior to and after the music and control sessions to determine whether stress, as measured by a hormone (i.e., cortisol), could be reduced by music. These samples were obtained by having subjects place a dental swab (dipped in sugar-free lemonade crystals) along their gumline for 30 seconds. The swab was then placed in a syringe, and the plunger was depressed to insert the saliva into a microcentrifuge tube. Saliva samples were frozen and assayed for cortisol at Duke University. Postsession salivary samples were collected 20 minutes following the end of the session due to a 20-minute lag in cortisol response time.

EEG Recording. EEG was recorded for 3 minutes prior to, during, and after the sessions. Subjects were instructed to look at a blue video screen monitor during each of these phases to control for artifact that may arise from visual stimulation.

EEG was recorded using a Lycra stretchable cap that was positioned on the subject's head using anatomical landmarks (Bloom & Anneveldt, 1982). Electrodes were positioned using the standard 10-20 system. Electrode gel was injected into the electrodes at sites F3, F4, P3, P4, and Cz (used as the reference), and impedances were brought below 5,000 ohms. Additional electrodes were positioned on the external can-thus and supraorbital position of one eye to record the subject's EOG (electrooculogram) for movement artifact scoring.

The signal was passed through a Grass Model 12 Neurodata Acquisition System with amplifiers set as follows: low frequency filter, 1 Hz; high frequency filter, 100Hz; amplification, 20,000. The line frequency filter was on for all channels. The output from the amplifiers was directed to a Dell 325D PC fitted with an Analog Devices RTI-815 A/D board. The signal was sampled at a rate of 512 Hz and streamed to hard disk using data acquisition software (Snapstream v. 3.21, HEM Data Corp., 1991).

EEG Analysis. EEG data were analyzed using an EEG analysis software package (EEG Analysis System v. 5.3, James M. Long, 1987-1990). The first step of this process involved the manual elimination of data that were unusable due to artifact (eye movements, muscle activity, or technical difficulties). The remaining artifact-free data were then spectrally analyzed using discrete Fourier transforms with a Hanning window of one-second duration to yield power data for specific frequency bands. The EEG power data were computed from 1 to 12 Hz in 1-Hz bins. Alpha was defined as 8 to 12 Hz, which accounted for the majority of the power in the EEG. Frontal alpha laterality ratios (FALR) were computed by dividing the difference between right and left frontal alpha powers by the sum of these powers (R-L/R+L). A score of zero represents hemispheric symmetry, a negative score represents greater relative right frontal activation, and a positive score represents greater relative left frontal activation. The adolescents' EEG w as expected to move from right frontal activation (negative scores) to symmetry (a zero score) or left frontal activation (positive scores) during or following the music session.

Music and Control Sessions

The adolescents listened to a selection of five popular songs (totaling 23 minutes): "Straight Up" by Paula Abdul (upbeat dance song), "Nasty" by Janet Jackson (upbeat dance song), "Vision of Love" by Mariah Carey (slow love ballad), "Greatest Love of All" by Whitney Houston (slow inspirational ballad), and "Keep the Faith" by Michael Jackson (moderate tempo, inspirational). These were selected by a group of female adolescents, who were similar to the study sample in age, ethnicity, and socioeconomic status, to ensure that the songs were culturally and developmentally appropriate, as well as either "uplifting" or ones that would make them "happy." During the music sessions, the songs were played through headphones on a high fidelity audio cassette player. The adolescents were informed that they would be videotaped as they listened to the music. Although their knowledge of being videotaped might contribute to faking good behavior, that effect was expected to be similar for both groups. The control subjects we re simply asked to relax their minds and muscles for the same 23-minute period.

Postsession Measures

Following the recording of the postsession EEG, saliva samples were collected for cortisol and the Depression Adjective Checklist (DACL) was administered. Subjects were also asked to complete the Music Rating Scale (MRS), in which they rated each music selection on a 6-point Likert scale, once for how the music made them feel and once for how much they liked the music. This scale was used to determine whether the subjects enjoyed listening to the particular music selected, because there were no effects for two pilot subjects who did not like rock music (positive effects were noted, however, when their favorite classical music was played).

RESULTS

A between groups (music versus control groups) repeated measures MANOVA was performed first, followed by ANOVAs on the Behavior Observation Scale, Depression Adjective Checklist, salivary cortisol, and frontal alpha laterality ratios, with presession, session, and post-session values as the repeated measures. Post hoc t tests were performed to examine significant interaction effects.

The adolescents averaged 22.3 on how the music made them feel and 23.4 on how much they liked the music (out of a possible MRS score of 30). No significant group effects or changes were noted for BOS or DACL scores (see Table 1). The music group's cortisol values, however, decreased significantly from presession to postsession. In addition, the music group's frontal alpha laterality ratios moved significantly closer to symmetry during and after the music session. Of the 14 adolescents in the music group, who initially showed right frontal EEG activation, 10 shifted toward left frontal EEG activation, 3 shifted toward more right frontal BEG activation, and 1 showed no shift in either direction. The control group's scores did not change significantly on any of the measures (see Table 1).

The 3 adolescents whose frontal activation values shifted further to the right were given a second session, in this case with classical music, which they preferred. During this session, their EEG values also shifted toward symmetry.

DISCUSSION

The behavior observations (BOS) and self-report data (DACL) yielded no changes during or following the music sessions. These findings differ from those in the literature, which has reported that music has positive effects on depressed behavior (Hanser, 1990; Williams & Dorrow, 1983) and self-reported mood state (Kenealy, 1988). In contrast, EEG and stress hormone levels in this study were significantly affected by music. In at least one previous study, psychophysiological measures (heart rate and systolic blood pressure) were positively affected by music (Pignatello, Camp, Elder, Thomas, & Rasar, 1989). Although the present music study is the first in which EEG and salivary cortisol were measured, the reductions in cortisol were similar to reductions noted after massage therapy with depressed adolescents (Field, Morrow, Valdeon, Larson, Kuhn, & Schanberg, 1992). This highlights the fact that it might not be music per se that has beneficial effects; rather, it is the mood induction procedure that is calming. The rock music was apparently "calming" for most of the adolescents in this study, although classical music was required for at least three of them. The fact that both vocal rock music and instrumental classical music could cause the same attenuation of right frontal EEG activation suggests that this shift was not caused by activation of the left hemisphere language center.

The change in EEG toward symmetry was surprising, since right frontal activation reportedly remains stable in chronically depressed adults even when remissions are noted in their behavior symptoms (Henriques & Davidson, 1990). However, no attempt was made in the Henriques and Davidson study to alter these EEG patterns. In the present study, EEG was altered from greater relative right frontal activation to lesser relative right frontal activation (or toward symmetry) even though no changes were noted in behavior or self-report.

The inconsistency between these and previously published data suggests that the subjects of this study may have been different from other samples. The subjects here were adolescents who were chronically but not clinically depressed. The inconsistency could also result from the procedures being slightly different across studies.

The incongruity between observed behavior, self-reported mood state, and the EEG and cortisol data was surprising given that these measures are usually complementary. This study has demonstrated that they certainly are not redundant. That the music subjects did not report a change in mood or show behavior change--yet showed EEG and cortisol changes--may be related to their having less control over EEG and cortisol levels than over self-report and behavior. Another possibility is that psychophysiological and biochemical changes occur more immediately than behavioral and "felt" mood state changes. Behavior and self-report changes might have been revealed had the subjects been monitored for a longer period of time. Further, the Behavior Observation Scale may have been too broad a rating system and the DACL may not have been sufficiently sensitive to mood state changes. In a future study, second-by-second behavior observations could be conducted and other confirmatory measures of mood added, such as the Profile of Mood States. Despite these caveats, the cortisol and EEG data suggest the strong effects of music in the direction of less depression and less anxiety.

The authors thank the adolescents who participated in this study and the research assistants and technicians who assisted with data collection and assays. This research was supported by an NIMH Research Scientist Award (#MH00331) and an NIMH Research Grant (#MH46586) to Tiffany Field.

Alex Martinez, B.A., and Thomas Nawrocki, B.A., Touch Research Institute, University of Miami School of Medicine.

Jeffrey Pickens, Ph.D., James Madison University.

Nathan A. Fox, Ph.D., Institute of Child Study, University of Maryland.

Saul Schanberg, M.D., Ph.D., Duke University Medical Center.

Reprint requests to Tiffany Field, Ph.D., Touch Research Institute, University of Miami School of Medicine, P.O. Box 016820, Miami, Florida 33101.

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