Prevalence and early determinants of common mental disorders in the 1982 birth cohort, Pelotas, Southern Brazil

OBJECTIVE: To estimate the prevalence of common mental disorders and assess its association with risk factors in a cohort of young adults. METHODS: Cross-sectional study nested in a 1982 birth cohort study conducted in Pelotas, Southern Brazil. In 2004-5, 4,297 subjects were interviewed during home visits. Common mental disorders were assessed using the Self-Report Questionnaire. Risk factors included socioeconomic, demographic, perinatal, and environmental variables. The analysis was stratified by gender and crude and adjusted prevalence ratios were estimated by Poisson regression. RESULTS: The overall prevalence of common mental disorders was 28.0%; 32.8% and 23.5% in women and men, respectively. Men and women who were poor in 2004-5, regardless of their poor status in 1982, had nearly 1.5-fold increased risk for common mental disorders (p=0.001) when compared to those who have never been poor. Among women, being poor during childhood (p=0.001) and black/mixed skin color (p=0.002) increased the risk for mental disorders. Low birth weight and duration of breastfeeding were not associated to the risk of these disorders. CONCLUSIONS: Higher prevalence of common mental disorders among low-income groups and race-ethnic minorities suggests that social inequalities present at birth have a major impact on mental health, especially common mental disorders.