The prevalence and course of chronic major depressive disorders (MDD) in the general population has rarely been assessed.

To gain a better understanding of the prevalence, course and the familial aggregation of MDD with at least one episode exceeding a duration of two years.

To assess 1) the prevalence; 2) course characteristics and comorbidity with other psychiatric disorders and 3) cardiovascular risk factors (CVRFs) and 4) the familial aggregation of chronic MDD in subjects with chronic MDD.

The sample stems from a large community survey carried out in the city of Lausanne, Switzerland. Subjects were aged from 35 to 65 years (n = 3717, 53.1% females, mean age: 50.9 years). They all underwent a physical examination of CVRFs and a psychiatric evaluation using the semi-structured Diagnostic Interview for Genetic Studies.

1) Approximately 15% of the sample reported at least one chronic depressive episode and 6% were in a chronic depressive episode at the time of the interview; about a 6th of them had episodes longer than 10 years; 2) compared to non-chronic MDD, MDD with chronic depressive episodes was associated with low socio-demographic level, comorbidity with anxiety disorders and almost all variables indicating poor course, but not with CVRFs except for inactivity; 4)there was no evidence for familial aggregation of chronic MDD.

As expected, MDD with chronic episodes revealed a strong association to indicators of poor course. However, with the exception of inactivity they do not seem to be associated with CVRF.