Gender differences in the etiology of anxiety sensitivity: a twin study.

OBJECTIVE

To estimate the magnitude of genetic and environmental factors on anxiety sensitivity by gender.

DESIGN

Classic twins reared-together study design.

PATIENTS: A community sample of 337 twin pairs, including 179 monozygotic (45 brother and 134 sister pairs) and 158 dizygotic (28 brother, 94 sister, and 36 brother-sister pairs).

METHOD: Twin pairs completed the Anxiety Sensitivity Index (ASI) using a postal survey design. The ASI is composed of three factors: (1) fear of anxiety-related somatic sensations; (2) fear of cognitive dyscontrol due to beliefs that sensations like depersonalization are signs of mental illness (e.g., fear of concentration problems); and (3) fear of publicly observable anxiety reactions (e.g., fear of trembling). Biometrical modeling techniques were used to estimate heritability of the ASI dimensions by gender.

RESULTS

ASI factors are heritable only in women, accounting for 37% to 48% of the total variance (median, 44.5%). Environmental factors accounted for all the variability in men.

CONCLUSIONS

These findings have implications for understanding the etiology of panic disorder. Previous research suggests that anxiety sensitivity is a risk factor or diathesis for this disorder, and that panic disorder is more prevalent in women than men. Our findings suggest the hypothesis that the increased prevalence in women may occur because anxiety sensitivity is heritable in women.