Dr. Mills Replies

To the Editor: We thank Drs. Sule and Kelly for their comments on our article and appreciate the opportunity to respond to their letter. A number of studies have found an association between antisocial personality disorder, substance use disorders, and PTSD. Nonetheless, we believe that our findings are unlikely to be confounded by antisocial personality disorder. First, antisocial personality disorder is an unreliable diagnosis, particularly among people with substance use disorders (1 , 2) . A diagnosis of antisocial personality disorder is based on behaviors often associated with drug use (e.g., criminality and social deviance) (3) . As such, it is difficult to distinguish “true psychopaths” (whose behaviors are driven by psychopathology) from “symptomatic psychopaths” (whose behaviors are driven by their drug use) (2 , 4) . Second, although it is true that antisocial personality disorder has been associated with considerable harm, when borderline personality disorder is controlled, the harms attributable to antisocial personality disorder disappear (1) . Finally, not one single respondent to the Australian National Survey of Mental Health and Well-Being screened positive for dissocial personality disorder (5) ; hence, it could not be controlled for in our study. This is unlikely because of the absence of the disorder in the Australian general population, but rather because of methodological limitations (5 , 6) and/or problems inherent in the operationalization of the disorder. We hope that our article, as well as the letter by Drs. Sule and Kelly, will contribute to future research in this area.