The present study aimed to explore the association between stressful life events (LE) and the development of affective psychopathology.

Thirty patients with unipolar disorder and 30 patients with bipolar disorder were compared to 60 matched healthy controls as regards the rate of stressful LE. Measures included the Beck Depression Inventory, the Adult Life Events Checklist and the Childhood Life Events Questionnaire.

The entire sample had more LE in general, more negative and loss-related LE in the year preceding their first depressive episode as compared to normals. Subjects with unipolar disorder had more positive LE and more achievement LE, whereas subjects with bipolar disorder had more uncontrollable LE in the year preceding the first depressive episode. The relationship between LE and manic episodes was prominent in the year preceding the first manic episode, with bipolar subjects reporting more LE in general and more ambiguous events in that year. A significant relationship was found between childhood LE and the development of affective disorders in adulthood, with unipolars exhibiting less positive and achievement LE.

The major impact of LE on the onset of affective disorders was found in the year prior to the first depressive or manic episodes, in the unipolar and bipolar groups. This suggests that the accumulation of LE at this crucial period contributes to the precipitation of a pathological response mechanism. Once established, this mechanism would be reactivated in the future by even less numerous and less severe stressors, compatible with the kindling hypothesis.