Relationships between suicidal ideation and the dimensions of depressive symptoms among middle-aged population in Japan.

BACKGROUND: The rate of suicides markedly increased in 1998 and leveled off at approximately 30,000 per year thereafter. The aim of the current study was to evaluate the link between the different dimensions of depressive symptoms and suicidal ideation among the middle-aged population in Japan.

METHOD: A sample of 6848 middle-aged (40-60years of age) working individuals completed the Center for Epidemiological Studies Depression Scale (CES-D) and a questionnaire measuring suicidal ideation. The responses on the four dimensions of depressive symptoms on the CES-D (depressed affect, lack of positive affect, somatic symptoms, and interpersonal problems) were entered into regression analyses that predicted the presence of suicidal ideation among the participants with probable depression (n=1704).

RESULTS: The factor score of depressed affect was significantly higher in females than in males, whereas that of interpersonal problems was significantly higher in males than in females. Among both males and females, depressed affect was a significant predictor of suicidal ideation. Among males, interpersonal problems also significantly predicted suicidal ideation. Contrary to the results of a previous study among adolescents, we did not find a relationship between lack of positive affect and suicidal ideation.

CONCLUSIONS: These findings indicate that the dimensions of depressive symptoms measured with the CES-D make different contributions to suicidal ideation. Although our results could not be generalizable to a clinical setting due to lacking clinical samples, the depressed affect dimension of CES-D might be useful for screening of suicide risk among community population. Furthermore, gender differences in the relationships between the dimensions of depressive symptoms in a middle-aged population were identified. Additional studies are needed to examine gender-specific relationships between the dimensions of depressive symptoms and suicidal ideation.