Co-Occurring Mental Illness and Substance Use Disorders: Associations Between Illness Severity, Perceived Need, and Receiving Substance Use Treatment
Shashim A. Waghmare, Riley D. Shearer, Joel E. Segel, Abenaa A. JonesObjective
To evaluate the association between mental illness severity, perceived need, and treatment for substance use disorder (SUD) outcomes among adults.
Methods
A repeated cross-sectional analysis using NSDUH 2021 to 2023 was conducted. Participants included adults aged 18 and over diagnosed with non-alcohol SUDs who met Diagnostic and Statistical Manual of Mental Disorders–V criteria for cocaine, hallucinogens, heroin, inhalants, marijuana, methamphetamine, pain relievers, sedatives, stimulants, or tranquilizers. The exposure was past year mental illness categorized as no mental illness, mild, moderate, and severe mental illness. Outcomes were past year SUD treatment receipt and perceived need for SUD treatment among adults with non-alcohol SUDs who did not receive treatment.
Results
Past year SUD treatment rates with no, mild, moderate, and severe mental illness were 7.3%, 11.1%, 14.4%, and 17.7%, respectively. Among adults with one or more non-alcohol SUDs, mild (aOR 1.39; 95% CI: 1.04–1.87), moderate (aOR 1.98; 95% CI: 1.34–2.92), or severe mental illness (aOR 2.47; 95% CI: 1.89–3.23) was associated with increased odds of receiving SUD treatment compared to no mental illness. Among individuals with non-alcohol SUDs who did not receive treatment, mild (aOR 2.40; 95% CI: 1.46–3.94), moderate (aOR 3.04; 95% CI: 1.83–5.05), and severe mental illness (aOR 4.30; 95% CI: 2.76–6.71) were associated with increased odds of seeking (but not receiving) treatment among those with perceived need.
Conclusion
With low overall SUD treatment uptake, greater severity of co-occurring mental illness is associated with higher treatment receipt and perceived need for care, highlighting the need for tailored strategies to improve access and retention.