Despite our substantially higher heritability estimate for PTSD, the associations observed in our sample between genetic and environmental factors that influence PTSD and those that influence AD are highly comparable to results from the VETR sample (the only other sample in which genetic overlap between the disorders has been studied). In Xian et al.’s (2000) study examining PTSD and AD in combination with drug dependence and also in Scherrer et al.’s (2008) study examining PTSD and AD with combat exposure, common genetic contributions to PTSD and AD were evident. Also consistent with our findings, Scherrer et al. (2008) found genetic overlap between combat exposure and PTSD.
