[Buffering effect of social support in the workplace on job strain and depressive symptoms].

OBJECTIVE The present study examined the buffering effect of social support in the workplace on job strain and depressive symptoms by conducting a cross-sectional survey using a self-report. METHODS The subjects were 712 employees (male, over 40 yr old) who worked at a precision machine factory. The questionnaire determined the subjects, ages, types of occupation, scores of depressive symptoms, job strain (job demand and job control), and social support (supervisor support and coworker support). Job strain and social support were evaluated by the Job Content Questionnaire (JCQ). The Center for Epidemiologic Studies Depression Scale (CES-D) score was measured and depressive symptoms were defined as a CES-D score > or = 16 point. Job strain and social support were calculated and divided into low-score groups (LG) and high-score groups (HG), respectively, by the median value. The mean values of CES-D in the LG and HG of job strain or social support were compared by the t-test. The hierarchical multiple regression was analyzed with the CES-D score as the dependent variable and by the characteristics of the participants, job strain and social support, and the cross-product interaction term of job strain and social support as independent variables. The effect of the degree of social support in the LG and HG of job strain on the CES-D score was evaluated by analysis of covariance adjusted for age. RESULTS The results showed that 23.2% of the workers had depressive symptoms, and that, the CES-D scores in the job demand group were significantly higher in HG than in LG. The CES-D scores in the job control, supervisor support, and coworker support groups were significantly higher in LG than in HG. The hierarchical multiple regression analysis showed that job demand, job control, supervisor support, and coworker support had significant main effects on the CES-D score. Furthermore, it was shown that there was a significant interaction in the CES-D score between job control and supervisor support, and that, the CES-D score in the supervisor support group was significantly higher in LG than that in HG only when job control was low. CONCLUSIONS These results suggest that supervisor support may have the effect of buffering depressive symptoms related to low job control.