Prevalence, Trends, and Disparities In Serious Mental Illness Diagnoses across Treatment Settings

Background and Purpose: Individuals with serious mental illnesses (SMI) are disproportionately represented in the criminal justice system, where they often receive mental health services, potentially reflecting gaps in access to community-based care. Prior research has identified demographic and structural factors associated with service utilization among individuals with SMI; however, limited research has examined whether the distribution of mental health diagnoses differs across community-based and justice-system treatment settings or how these patterns change over time. Additionally, it remains unclear whether demographic characteristics are associated with diagnosis patterns within these settings. This study examines: (1) the prevalence of primary SMI diagnoses across treatment settings, (2) changes in diagnosis prevalence over time, and (3) demographic factors associated with the likelihood of specific diagnoses within these settings.

Methods: This study uses quantitative methods with administrative data from the Substance Abuse and Mental Health Services Administration Mental Health Client-Level Data (MH-CLD) dataset. The sample includes individuals receiving mental health services in both community-based and justice-system settings across five years who meet criteria for SMI diagnoses. Descriptive trend analyses were conducted to assess changes in diagnosis prevalence over time and across settings. Multinomial logistic regression models were used to estimate the odds of specific diagnoses (e.g., schizophrenia, bipolar disorder, personality disorders) as a function of demographic characteristics (e.g., age, gender) within and across treatment settings. Model results are presented as odds ratios and 95% confidence intervals (CI).

Results: Across the five-year period, schizophrenia had the highest prevalence in each setting—73%–77% in justice-system settings and 50%–51% in community-based settings. Bipolar disorder followed (20%–22% and 46%–47%, respectively), while personality disorders remained lowest (3%–5% and 3%–4%). Males in justice-system settings were more likely than females to be diagnosed with personality disorders than schizophrenia (OR = 3.65, 95% CI = 3.43, 3.88). In contrast, among those in community settings, males were least likely to be diagnosed with schizophrenia than a bipolar disorder (OR = .30, 95% CI = .30, .30). Additionally, younger adults were more likely than older adults to be diagnosed with personality disorders relative to schizophrenia in community-based settings (OR = 1.83, 95% CI = 1.76, 1.90) while they were more likely to be bipolar disorder relative to schizophrenia in justice-system settings (OR = 1.87, 95% CI = 1.64, 2.12).

Conclusions and Implications: These findings highlight disparities in SMI diagnoses across treatment settings and the influence of demographic factors on diagnostic patterns. People with schizophrenia are disproportionately represented in justice-system settings, and age and gender significantly predict diagnosis within each setting. Individuals with schizophrenia often experience acute, observable symptoms that increase the likelihood of crisis involvement and law enforcement contact. Structural factors, including limited access to early intervention and fragmented continuity of care, may funnel individuals with untreated symptoms into justice-system settings. These disparities likely reflect differences in access to care, diagnostic practices, and systemic inequities, underscoring the need for improved community-based services and targeted interventions.