Generalized anxiety disorder in women: A population-based twin study

Little is known about the role of familial and genetic factors in the etiology of generalized anxiety disorder (GAD), a new disorder first proposed in DSM-III. We examine this question in 1033 female-female twin pairs from a population-based registry. Both members in each twin pair were "blindly" assessed by structured psychiatric interview. Our results suggest the following: GAD is a moderately familial disorder the tendency for GAD to run in families seems to be due largely or entirely to genetic factors shared between relatives rather than to the effects of the familial environment the heritability of GAD, estimated at around 30%, is modest, with the remainder of the variance in liability resulting from environmental factors not shared by adult twins the heritability of GAD cannot be explained solely by the occurrence of GAD only during episodes of major depression or panic disorder the etiologic role of genetic factors is probably similar in GAD with a 1- vs a 6-month minimum duration of illness. (April 1992)