Genetic and environmental effects on self-reported depressive symptoms in a general population twin sample (original) (raw)

1990, Journal of Psychiatric Research

To determine the etiology of self-reported depressive symptoms and their co-occurrence in the general population, multivariate genetic models were fitted to the responses of 771 female twin pairs (463 MZ, 308 DZ) to a 20-item epidemiological depression inventory (CES-D scale). A model which contained one common genetic factor, one shared environmental factor, and four unique environmental factors provided a useful account of symptom covariation. Under this model, the four non-shared environmental factors explained the largest proportion of variance in response to the CES-D scale, whereas a single common genetic factor explained substantially less of the variation in symptomatology. Consistent with previous findings (KENDLER, HEATH, MARTIN, & EAVES, Archives of Genera/ Psychiafry 43, 213-221, 1986) shared environmental influences were found to play a relatively minor role in the report of depressive symptoms. These results suggest that while genetic factors do contribute to the covariation among symptoms of depression, it is the largely non-shared environmental factors that account for the co-occurrence of symptoms in the general population. 1NTRODUCTlON EVIDENCE from numerous twin, family, and adoption studies has demonstrated the importance of both genetic and environmental factors in affective illness. In a review of the twin literature on affective disorders GERSHON, BUNNEY, LECKMAN, VAN EERDEWEGH, and DEBAUCHE (1976) reported an overall concordance rate of 69.2% for monozygotic twins and 13.3% for dyzygotic twin pairs, providing support for a genetic predisposition to this disorder. Genetic effects have been relatively well established in bipolar depression (WINOKUR &