Background: This study examined trends in selected mental health diagnoses among patients admitted to specialty addiction treatment programs in the United States from 2006 to 2022.

Methods: Joinpoint regression was used to examine annual data from the publicly available Treatment Episode Data Set – Admissions. Sample selection criteria included having a primary substance listed and any of the following conditions: (a) anxiety disorders, (b) bipolar disorders, (c) depressive disorders, and (d) schizophrenia and other psychotic disorders.

Results: Among 31,152,649 admissions, anxiety disorders accounted for 0.1%, bipolar disorders 0.3%, depressive disorders 0.4%, and schizophrenia/psychotic disorders 0.1%. The final sample included 224,051 admissions: anxiety disorders (13.0%; n=29,111), bipolar disorders (30.3%; n=67,926), depressive disorders (43.4%; n=97,293), and schizophrenia/psychotic disorders (13.3%; n=29,721). Significant declines were observed in admissions involving bipolar disorders (−12.29%, 2008–2022), depressive disorders (−16.69%, 2019–2022), and schizophrenia/psychotic disorders (−6.96%, 2006–2022).

Conclusion: Findings highlight the need for improved screening, diagnostic recording, and epidemiological research on co-occurring mental health and substance use disorders.