Epidemiology of depression.

Review of the published literature produces 1-year prevalence rates for major depressive disorder DSM-III between 2.6 and 6.2%, for dysthymia between 2.3 and 3.7%, bipolar disorder 1.0-1.7%. Data from the prospective Zurich Study with four interviews over 10 years give relatively high 10-year prevalence rates for subjects from age 20 to 30 (14.4% major depression, 10.5% recurrent brief depression, 0.9% dysthymia, 3.3% bipolar disorder, 1.3% hypomania). On average, 49% of all these cases received treatment for affective disorder, resulting in a weighted treatment prevalence rate of the population of 11.6% (18% for females and 5% for males). It has to be assumed that lifetime prevalence rates based on recall may greatly underestimate true morbidity.