Psychological distress is a health issue of critical importance, especially in people of working age in developed countries, including Japan. This study examined the relationships of income and employment arrangement with psychological distress and treatment of depression in a national sample of Japanese adults.

Data for 10,959 men and 11,655 women 25–59 years of age, obtained from the Comprehensive Survey of the Living Conditions of People on Health and Welfare in 2007, were examined. Health outcomes were psychological distress measured by the Japanese version of the K6, subjective complaints and medical treatment of depression. Explanatory variables included marital status, employment arrangement, and household income. The relationships between health outcomes and explanatory variables were examined using multiple logistic regression analyses.

Lower income and unemployment were associated with a higher prevalence of psychological distress and treatment of depression. The association between psychological distress and income showed a threshold: the lowest income quintile had an especially high prevalence, while other quintiles had similar prevalences. The prevalence of depression treatment in those with psychological distress was significantly lower in the highest income quintile than in all the other income groups, and the prevalence was also significantly lower in employed than in unemployed respondents.

This study showed clear relationships of lower income and unemployment with psychological distress and depression treatment. It has been suggested that people with higher socioeconomic status and full-time work may be reluctant to consult professionals and receive medical treatment, despite their psychological distress. Comprehensive mental health interventions are required to prevent psychological distress in all socioeconomic strata of the population.