THE PREDICTION OF MAJOR DEPRESSION IN WOMEN - TOWARD AN INTEGRATED ETIOLOGIC MODEL

Objective: The authors develop an exploratory, integrated etiologic mo del for the prediction of episodes of major depression in an epidemiol ogic sample of women. Method: Both members of 680 female-female twin p airs of known zygosity from a population-based register were assessed three times at greater than 1-year intervals. The last two assessments included a structured interview evaluation for presence of episodes o f major depression, defined by DSM-III-R, in the preceding year. The f inal structural equation model contained nine predictor variables: gen etic factors, parental warmth, childhood parental loss, lifetime traum as, neuroticism, social support, past depressive episodes, recent diff iculties, and recent stressful life events. Results: The best-fitting model predicted 50.1% of the variance in the liability to major depres sion. The strongest predictors of this liability were, in descending o rder, 1) stressful life events, 2) genetic factors, 3) previous histor y of major depression, and 4) neuroticism. While 60% of the effect of genetic factors on the liability to major depression was direct, the r emaining 40% was indirect and mediated largely by a history of prior d epressive episodes, stressful life events, lifetime traumas, and neuro ticism. The model suggested that at least four major and interacting r isk factor domains are needed to understand the etiology of major depr ession: traumatic experiences, genetic factors, temperament, and inter personal relations. Conclusions: Major depression is a multifactorial disorder, and understanding its etiology will require the rigorous int egration of genetic, temperamental, and environmental risk factors.