Age and birth cohort differences in depression in repeated cross-sectional surveys in England: the National Psychiatric Morbidity Surveys, 1993 to 2007.

Background: The National Psychiatric Morbidity Survey (NPMS) programme was partly designed to monitor trends in mental disorders, including depression, with comparable data spanning 1993 to 2007. Findings already published from this programme suggest that concerns about increasing prevalence of common mental disorders (CMDs) may be unfounded. This article focuses on depression and tests the hypothesis that successive birth cohorts experience the same prevalence of depression as they age.

Method: We carried out a pseudo-cohort analysis of a sequence of three cross-sectional surveys of the English household population using identical diagnostic instruments. The main outcome was ICD-10 depressive episode or disorder. Secondary outcomes were the depression subscales of the Clinical Interview Schedule - Revised (CIS-R).

Results: There were 8670, 6977 and 6815 participants in 1993, 2000 and 2007 respectively. In men, the prevalence of depression increased between cohorts born in 1943-1949 and 1950-1956 [odds ratio (OR) 2.5, 95% confidence interval (CI) 1.4-4.2], then remained relatively stable across subsequent cohorts. In women, there was limited evidence of change in prevalence of depression. Women born in 1957-1963, surveyed aged 44-50 years in 2007, had exceptionally high prevalence. It is not clear whether this represents a trend or a quirk of sampling.

Conclusions: There is no evidence of an increase in the prevalence of depression in male cohorts born since 1950. In women, there is limited evidence of increased prevalence. Demand for mental health services may stabilize or even fall for men.