Predictors of new-onset depressive disorders - Results from the longitudinal Finnish Health 2011 Study.

BACKGROUND: Identifying risk factors for depression is important for understanding etiological mechanisms and targeting preventive efforts. No prior studies have compared risk factors of dysthymia and major depressive disorder (MDD) in a longitudinal setting. METHODS: Predictors of new-onset MDD and dysthymia were examined in a longitudinal general population study (Health 2000 and 2011 Surveys, BRIF8901). 4057 persons free of depressive disorders at baseline were followed up for 11 years. DSM-IV MDD and dysthymia were diagnosed with the Composite International Diagnostic Interview. RESULTS: 126 persons (4.4%, 95%CI 3.6-5.2) were diagnosed with MDD or dysthymia at follow-up. Predictors of new-onset depressive disorders were younger age (adjusted OR 0.97, 95%CI 0.95-0.99 per year), female gender (aOR 1.46, 95%CI 1.01-2.12), multiple childhood adversities (aOR 1.76, 95%CI 1.10-2.83), low trust dimension of social capital (aOR 0.58, 95%CI 0.36-0.96 for high trust), baseline anxiety disorder (aOR 2.75, 95%CI 1.36-5.56), and baseline depressive symptoms (aOR 1.65, 95%CI 1.04-2.61 for moderate and aOR 2.49, 95%CI 1.20-5.17 for severe symptoms). Risk factors for MDD were younger age, female gender, anxiety disorder and depressive symptoms, whereas younger age, multiple childhood adversities, low trust, and having 1-2 somatic diseases predicted dysthymia. LIMITATIONS: We only had one follow-up point at eleven years, and did not collect information on the subjects' health during the follow-up period. CONCLUSIONS: Persons with subclinical depressive symptoms, anxiety disorders, low trust, and multiple childhood adversities have a higher risk of depressive disorders. Predictors of MDD and dysthymia appear to differ. This information can be used to target preventive efforts and guide social policies.