background If clinicians are informed about the duration of depressive episodes and they know what factors determine the future course of the illness they should be able to make more accurate prognoses.
aim To present an overview of research data relating both to the duration of depressive episodes and to the determinants of the course of the illness.
method Results of research done on this subject in other countries and results of the Netherlands Mental Health Survey and Incidence Study (nemesis) are presented. Articles were selected by reason of their sound methodology.
results The median duration of new or recurrent depressive episodes (dsm-iii-r or iv) is 3 to 5 months. The condition becomes chronic (the depression lasts for at least 2 years) in 9 to 20% of individuals with depression. The best predictors of the persistence of the depression are factors such as the severity of the depressive episode and the increased longer duration of earlier episodes. Other determinants of persistence are previous (physical or psychiatric) illness, lack of support and experience of difficulties in life over long periods.
conclusion If depressed patients fail to recover within 3 to 5 months, there is a considerable risk that the condition will become chronic. It is important that a treatment programme for depression takes into account the current duration of a patient's depressive episode and other factors that are predictors of persistence.