The present study has implications for future research on substance abuse and SMI. Our results indicate that substance use, while a common a prevalent problem in SMI, is not the same for everyone. There appears to be remarkable and complex heterogeneity in substance use patterns by psychiatric diagnosis and genders, signaling sub-groups that may show differences in etiology, maintaining factors and treatment needs. Thus, our findings suggest characterizing the factors associated with poor outcomes may be critical to facilitating effective treatments for substance abuse in this population. Indeed, there is a diagnostic dilemma in terms of whether SMI is associated with primary or induced SUD [36, 55–63], and thus an accurate psychiatric diagnosis is a key component of substance use treatment planning [36]. Delivering treatments for substance abuse presents challenges for mental health professionals [64], and there is seemingly no consensus on a recommended model of intervention to follow in these patients [36], although models employing integrated treatment for co-occurring disorders have a solid evidence base [68–69]. Regardless, the preponderance of the evidence indicates combinations of psychotherapies, behavioral and pharmacological
