In addition, the current study investigated associations between PTSD PRS, PTSD, and different substance dependence diagnoses simultaneously. While this statistical model allowed the diagnoses to covary, it is not a test of comorbidity (i.e., the model does not predict the relationship between PTSD PRS and co-morbid diagnoses). Since studies, including the current study, have demonstrated the importance of investigating PTSD and substance use disorders together, future studies with larger sample sizes should investigate genetic risk of comorbid PTSD and substance dependence, especially alcohol dependence.
