Role of multiple risk factors in mental disorders diagnosed in middle-aged women: A population-based follow-up study

The aims of the study were 1). to investigate the association between the potential risk factors including socio-demographic, lifestyle and DNA methylation and mental disorders in middle-aged women from a large population-based follow-up study, and 2). to estimate the risk score by combining the potential risk factors to examine the mental disorder's incidence. A total of 6461 women, aged 50-65 years, were included in the study. After a median follow-up of 17 years, 2026 (31%) women were diagnosed with mental disorders. The association between these factors and the risk of mental disorders was analyzed using Cox regression models. Harrell's concordance index (C-index) was used to quantify models' predictive performance for future mental disorders. Blood-based global DNA methylation was assessed by an enzyme-linked immunosorbent assay. We found that smoking (HR = 1.38, 95% CI: 1.24-1.54), less physical activity (HR = 1.33, 95% CI: 1.10-1.60), being single (HR = 1.16, 95% CI: 1.04-1.29) and unemployment (HR = 1.50, 95% CI: 1.33-1.70) were independently associated with an increased risk of overall mental disorders. Risk score models combining all these observed factors showed an increased risk, but the prediction ability was low, except for the risk of alcohol use disorders (AUD) and drug use disorders (DUD) (C-index = 0.8). Finally, women who developed MDD/anxiety during follow-up had significantly higher global DNA methylation at baseline than women who did not develop MDD/anxiety (p = 0.005). In conclusion, our results indicate that the studied risk factors were associated with mental disorders in a type-specific manner. The predictive model showed that smoking, alcohol consumption, education and physical activity may predict future AUD/DUD. Global DNA methylation may be a potential risk factor for MDD/anxiety incidence.