Reconfirming the role of life events for the timing of depressive episodes. A two-year prospective follow-up study

Abstract

Background: Since the 1960s the association of stressful life events and depression seemed to be firmly established. However, a few recent studies did not confirm those earlier findings. One of the reasons discussed for the inconsistencies was the sampling of milder depressed neurotic out-patients in the earlier studies vs. more severely ill endogenous type in-patients in recent studies.

Methods: This investigation was carried out with 50 consecutively admitted in-patients with endogenous depression according to ICD 9 and unipolar major depression according to DSM-III-R as ascertained by SCID. The control sample consisted of 26 healthy volunteers. Life events and chronic distressing life conditions were recorded with the Munich Interview for the Assessment of Life Events and Conditions (MEL) every 3 months over a period of 2 years along with psychopathological symptoms and recurrencies. Hence the design was prospective in the sense that life events were recorded for one 3-month cross-section, the depressive reaction for the subsequent one. BDI scores taken at the respective cross section were used to control for depressive bias of the subjective part of the patient's life event evaluation.

Results: Three months prior to the index hospitalization patients were more often affected by life events and conditions than controls. The number of stressful conditions prior to the index hospitalization indicated the time to relapse after discharge. Controls showed more desirable positive conditions than patients. Relapse patients suffered more often stressful life events and conditions than non-relapsers 3 months prior to their relapse. Multivariate analysis indicates that the cumulative number of life events within the 2-year course is the best predictor of the BDI score at the end of the follow-up period.

Limitations: Since the subjective component of life event assessment by MEL displayed a higher impact on the course of depression than the objective part of the assessment, confounding of subjective ratings, attributional styles, and depressive symptoms may be a problem although controlled for in this study.

Conclusion: The results support the importance of stressful life events and chronic distressing conditions for the 2-year course and outcome of major depression in an in-patient sample. Since the overall consistency of significant results was more pronounced in the subjective than in the objective part of the MEL the results fit best a circular pathogenetic model of interactions between life events, their individual evaluation by the patient, and depressive symptoms.