Toward Understanding Sex Differences in the Prevalence of Posttraumatic Stress Disorder: Results From the National Epidemiologic Survey on Alcohol and Related Conditions

Background: It is unclear whether the higher prevalence of posttraumatic stress disorder (PTSD) in women than in men is due to sex differences in the prevalence of the exposure to traumatic events or to differences in vulnerability to traumatic events among those exposed to them.

Methods: We applied mediation and moderated mediation models to a large nationally representative sample of US adults (N = 34,653) drawn from Wave 2 (2004-2005) of the National Epidemiologic Survey on Alcohol and Related Conditions.

Results: A model that assumed that the effect of 19 traumatic events was the same across sexes and examined whether sex differences in the prevalence of DSM-IV PTSD were due exclusively to sex differences in exposure to traumatic events predicted similar prevalence of PTSD among men and women (indirect effect standardized β = 0.04, P = .61), contrary to empirical findings. By contrast, a model that allowed the effect of 19 traumatic events on risk of PTSD to vary by gender, while taking into account sex differences in the prevalence of exposure, indicated that, for 13 of the traumatic events, the effect was significantly greater in women than in men (range of standardized β coefficients = 0.02-0.12, P < .05). The total indirect and direct effects of sex on PTSD in this model were, respectively, β = 0.42 (P < .01) and β = −0.03 (P = .76), indicating that all of the effect of sex on PTSD was explained by this moderated mediation model.

Conclusions: The higher prevalence of PTSD among women appears to be due mainly to their greater vulnerability to the effects of traumatic events.