Are Socioeconomic Disadvantages Leading Women to a Higher Risk of Depression, Anxiety and Common Mental Disorders? Disentangling the Role of Schooling and Income in a Birth Cohort Study from Brazil

Abstract

Background: Reasons for the higher risk of depression, anxiety and common mental disorders among women are unclear. In the present study, we investigated the mediating effect of schooling and personal income in adulthood and the effect modification of maternal schooling and income at birth. Methods: In 1982, the maternity hospitals of Pelotas (Southern Brazil) were daily visits and those livebirths whose family lived in the urban area of the city were examined and their mothers interviewed. These subjects have been followed-up for several time. At 30 years, the presence of major depression (MD) and generalized anxiety disorder (GAD) was assessed using the Mini-International Psychiatric Interview, and common mental disorders (CMD) with the self-rated questionnaire. We used Mantel-Hanszel test for effect modification and a counterfactual framework using inverse probability weights (IPW) and G-computation to analyse mediation. Outcomes: Income at 30 years captured part of the association of sex with MD (16.5%), GAD (14.2%), and CMD (18.0%). Schooling at 30 years was higher in women (p<0.001), and inversely mediated the association with MD (-5.4%), GAD (-4.8%), and CMD (-6.7%). If we fixed the mediator to earning more than 3 minimum salaries, the effect of sex, was reduced in 64.9%, 56.7% and 31.4%, for MD, GAD and CMD, respectively, and 62.4%, 13.6% and 23.8%, if fixed to 12 or more years of schooling. Interpretation: Personal income and schooling at 30 years, are mediators and effect modifiers of the association between sex and MD, GAD and CMD. Funding: Wellcome Trust. Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: We obtained ethical approval for the study from the ethics committee of the ‘Universidade Federal de Pelotas’, all participants signed an informed consent.