PANIC DISORDER IN WOMEN - A POPULATION-BASED TWIN STUDY

Previous studies based on probands from clinical samples suggest that panic disorder aggregates strongly in families and may be due to a hig hly penetrant single major locus. In this study we examine panic disor der as assessed at blind, structured psychiatric interview in 2163 wom en from a population-based twin registry. DSM-III-R diagnoses were ass igned at a narrow and at a broad level both by clinician review and by computer algorithm. The familial aggregation of panic disorder in thi s sample was only modest. The relatively small number of affected indi viduals prevented a definitive resolution of competing genetic and non -genetic models of familial transmission. Although there was some inco nsistency across diagnostic approaches, most results suggested that th e familial aggregation of panic disorder was due largely to genetic fa ctors. Using a multifactorial-threshold model, the best estimates of t he heritability of liability ranged from 30 to 40 %. From a familial p erspective, panic disorder with phobic avoidance appears to represent a more severe form of the syndrome than panic disorder without avoidan ce. Our results, which suggest that in the general population panic di sorder is only a moderately heritable condition, are at variance with results from several previous investigations based on clinically ascer tained samples.