Background. Adverse life events and social support may influence the outcome of major depressive disorder (MDD). We hypothesized that outcome would depend on the level of depressive symptoms present at the outset, with those in partial remission being particularly vulnerable.

Method. In the Vantaa Depression Study (VDS), patients with DSM-IV MDD were interviewed at baseline, and at 6 and 18 months. Life events were investigated with the Interview for Recent Life Events (IRLE) and social support with the Interview Measure of Social Relationships (IMSR) and the Perceived Social Support Scale – Revised (PSSS-R). The patients were divided into three subgroups at 6 months, those in full remission (n=68), partial remission (n=75) or major depressive episode (MDE) (n=50). The influence of social support and negative life events during the next 12 months on the level of depressive symptoms, measured by the Hamilton Rating Scale for Depression (HAMD), was investigated at endpoint.

Results. The severity of life events and perceived social support influenced the outcome of depression overall, even after adjusting for baseline level of depression and neuroticism. In the full remission subgroup, both severity of life events and subjective social support significantly predicted outcome. However, in the partial remission group, only the severity of events, and in the MDE group, the level of social support were significant predictors.

Conclusions. Adverse life events and/or poor perceived social support influence the medium-term outcome of all psychiatric patients with MDD. These factors appear to have the strongest predictive value in the subgroup of patients currently in full remission.