Treated versus non-treated subjects with depression from a 30-year cohort study: prevalence and clinical covariates

The aim of this study was to determine prevalence rates of several components of depression (unipolar and bipolar major, minor, recurrent brief depression, and dysthymia) and to identify covariates of treatment. We analysed a representative population-based, long-term prospective cohort study from age 20 to 50. Across the seven semi-structured interviews, generalized estimating equations examined the associations between diagnoses and treatment status during the course. The results show that the mean annual treatment rate across 30 years in persons with MDE was 39.2 %. The weighted treatment prevalence for any depressive disorder was 23.4 % (15.7 % for MDE, 4.3 % for minor depressive disorders and 3.4 % for non-diagnosed subjects). Persons were more likely to seek treatment as they grew older. Women with MDE had triple the treatment prevalence of men (23.8 vs. 7.4 %). Variables of distress/suffering under depression (OR 1.36–1.52) and the number of diagnostic depressive symptoms (OR 1.47) were statistically significant predictors of treatment, as were episode duration (OR 2.21) and various variables assessing impairment due to depression (OR 4.65–8.02). In conclusion, only a minority of persons with depressive disorders seek professional treatment in the year of disorder onset. Women and subjects suffering from high levels of depressive symptoms, frequent episodes, long episode duration and consecutive high distress and impairment were more likely to seek treatment.