Substance Use Disorders and Psychiatric Illness Among Transitional Age Youth Experiencing Homelessness.

Objective: Transitional age youth experiencing homelessness (TAY-EH) bear a high burden of substance use disorders (SUDs) and psychopathology. However, limited data exist on the co-occurrence and interactions between these diagnoses in this marginalized group. This study sought to identify rates of single and co-occurring SUDs and psychiatric diagnoses among a sample of TAY-EH and to investigate associations between psychopathology and prevalence and severity of SUDs in this group. Method: TAY-EH accessing a low-threshold social service agency in a large metropolitan area completed psychosocial and diagnostic interviews to assess for SUDs and psychopathology. Analyses examined rates of single and co-occurring disorders and associations between burden of psychopathology and presence and severity of SUDs. Results: The assessment was completed by 140 TAY-EH; the majority were youth of color (54% Black/African American, 16% Latinx), and 57% identified as male. Rates of single and co-occurring psychiatric disorders and specific SUDs (cannabis use disorder [CUD] and alcohol use disorder [AUD]) were notably high. An increasing number of psychiatric diagnoses was significantly associated with elevated CUD/AUD prevalence and severity. Mood, anxiety, attention-deficit/hyperactivity, and antisocial personality disorders were significantly associated with elevated CUD/AUD prevalence and severity, as was suicidality (all Conclusion: This study reveals a complex overlay of SUDs and psychopathology facing TAY-EH, with a significant association between co-occurring psychopathology and severity of CUD/AUD. To the authors' knowledge, this is the first study to examine associations between specific psychopathology and severity of SUDs among TAY-EH. Further research into the mechanistic and temporal links between these conditions is needed to inform tailored treatment interventions.