A multidimensional twin study of mental health in women

Objective: While researchers have increasing insight into the role of genet ic and environmental factors in the etiology of psychiatric and substance u se disorders, they know much less about how such factors influence the dime nsions of healthy psychological functioning. Method: In a population-based sample of 794 female-female twin pairs, the authors examined, by using mult ivariate structural equation modeling, six dimensions of mental health: per ceived physical health, nonconflictual interpersonal relationships, anxious -depressive symptoms, substance use, social support, and self-esteem. Resul ts: The best-fit model was complex and constituted five common factors (two genetic, one family environmental, and two unique environmental); variable -specific genetic effects for physical health, substance use, and social su pport; and variable-specific family environmental effects for interpersonal relationships and substance use. Genetic effects were seen for all six dim ensions; total heritabilities ranged from 16% to 49%. Family environment wa s an important influence on interpersonal relationships, substance use, and social support. Conclusions: Mental health is a complex phenotype that is influenced by a diverse array of genetic and environmental factors. While g enetic factors appear to be of moderate etiologic importance in all major d imensions of mental health, the family environment is an important influenc e on only interpersonal relations, social support, and substance use.