Posttraumatic Stress Disorder and Substance Use Disorder Comorbidity in Homeless Adults: Prevalence, Correlates, and Sex Differences

Substance use disorders (SUDs) are highly prevalent in homeless populations, and rates are typically greater among males. Posttraumatic stress disorder (PTSD) is a common co-occurring condition among individuals with SUDs; however, little attention has been directed to examining this comorbidity in homeless populations. Although some studies indicate considerable sex differences among individuals with PTSD, it has also been suggested that sex differences in PTSD rates diminish in populations with severe SUDs. This cross-sectional study investigated SUD-PTSD comorbidity and its associations with indicators of psychosocial functioning in a sample of 500 homeless individuals from Canada. Sex-related patterns of SUD, PTSD, and their comorbidity were also examined. Males and females had similar SUD prevalence rates, but the rates of PTSD and PTSD-SUD comorbidity were higher in females. PTSD and sex were found to have significant main effects on suicidality, psychological distress, somatic symptoms, and incarceration among individuals with SUD. Sex also moderated the association of PTSD with suicide risk and psychological distress. Our results contradict assumptions that sex differences in PTSD rates attenuate in samples with severe SUDs. Organizations providing SUD treatment for homeless people should address PTSD as an integrated part of their services. SUD and integrated treatment programs may benefit from sex-specific components.