Study limitations include the fact that the current study relies on summary statistics from individuals of European ancestry only given that LDSC is currently only applicable to non-admixed samples. The inclusion of individuals of diverse ancestry is a critical next step to reduce disparities in the representation of, and applicability of genetic results to, global populations. Although the AD summary statistics used in the present study are from one of the largest publicly available AD GWAS datasets, it is noted that the sample size is still fairly small from a GWAS perspective. Related to this limitation, male and female specific AD summary statistics were not used in the current study due to the lack of statistical power for sex-stratified analyses noted by Walters et al. (2018). A related limitation is that it thus remains unknown whether sex differences in shared heritability are attributable to PTSD and/or AD. As GWAS sample sizes for AD increase, male and female specific AD heritability estimates and genetic correlations with PTSD should be examined. The current study relies on summary statistics from the two largest
