However, the relationship between psychiatric and SUD comorbidity and illness severity and impairment is not necessarily consistent across domains of illness severity and impairment and may be the result of multiple concurrent psychiatric disorders rather than a single comorbid psychiatric disorder. For example, Mills and colleagues (2007) reported that opiate dependent treatment recipients with PTSD (compared to those who did not meet criteria for PTSD) were less likely to be employed, more impaired physically and psychosocially, and more likely to have a history of overdose or suicidality, but they also reported using heroin less frequently in the past month, reduce heroin use as successfully, and did not report higher levels of other drug use. Participants with PTSD in the Mills et al. (2007) study also were 1.6–2.5 times more likely than those without PTSD to meet criteria for major depression, ASPD, and borderline personality disorder as well as PTSD. Another study of opiate dependent treatment recipients found that PTSD was associated with a longer history of drug use and more severe psychiatric symptoms than patients not diagnosed with PTSD, but comparable reductions in heroin, cocaine, and alcohol use and better treatment attendance and retention (Trafton et al., 2006).
