Information on the epidemiology of depressive disorders is essential for providing a framework for the formulation of effective mental health policies. In the last 15 years, some population surveys of psychiatric morbidity in adults have been conducted and, as a result, details on the frequency, risk factor, social disabilities, and service use are now available. Epidemiological findings for depressive illness are discussed on the light of results from recent mass surveys namely the Epidemiological Catchment Area Study (ECA), the National Comorbidity Survey (NCS), the OPCS Survey of Psychiatric Morbidity in Great Britain, the Brazilian Multicentric Study of Psychiatric Morbidity, and other surveys on common mental disorders conducted in Brazil. Prevalence rates for major depression disorder, dysthymia, and other depressive states are high for all estimates, regardless setting, the type of instrument used for generating psychiatric diagnosis, and the time periods by which prevalence is defined. Depression is more common among women, divorced or separated people, those living in one-person family units, with lower level of education and income, unemployed and urban dwellers. Depressed subjects are more likely to have medical consultations and in-patient episodes. The cost-effectiveness of treatments must be balanced with the high individual and social impact associated to depressive illness.
Depression; depressive disorders; prevalence; incidence; social impact