Trends in Substance Misuse and Housing Instability of Service Users with Personality Disorder: Insights from the 2013-2022 Mental Health Client-Level Data

Background and Purpose: Substance misuse in the context of personality disorder (PD) is influenced by a complex interplay of individual and socioenvironmental factors. Housing instability is one such factor that may share reciprocal relationships with substance misuse. PD and substance misuse can contribute to social or occupational impairments that exacerbate the risk of becoming unhoused, and the social stigma associated with each condition can undermine access to adequate supportive services. In the unhoused context, substance use may be motivated by the environmental stressors associated with lacking adequate housing. As housing instability and homelessness is a growing social problem in the United States and people with PD experience increased risk of homelessness, this study investigates trends in documented substance misuse by housing status among recipients of publicly funded mental health service with PD.

Methods: This study used 2013–2022 Mental Health Client-Level Data (N=61,631,122), which collects demographic, behavioral health, and service data on recipients of publicly funded US mental health services. The study sample included participants with valid housing status and substance use data who were diagnosed with any PD, aged 18 years or older, and received community-based services within the US (4.94%; n=167,547). Trends in substance misuse were tested, stratified by housing status, and adjusted for demographic and service use characteristics. We used multivariate logistic regression to identify clinical and demographic correlates of substance use difficulties and to explore trends in substance use difficulties over the study period by housing type. Predicted probability of substance use difficulties was calculated for each housing status over each year of data.

Results: Overall, Substance use difficulties were documented in 47.43% (n=553,781) of the sample, with the proportion of clients with documented substance misuse increasing over study years (OR=1.05, 95%CI:1.05, 1.05). Substance misuse was more frequently documented in unhoused (64.3%) and institutionally housed (58.6%) service recipients relative to privately housed service users (44.3%; p<.001). Service users who were indigenous (OR=1.40, 95%CI:1.35, 1.45), Black (OR=1.18, 95%CI:1.17, 1.20) or other races (OR=1.37, 95%CI:1.34, 1.39) high higher odds of documented substance misuse relative to White service users. Asian (OR=0.58, 95%CI:0.55, 0.61) and Pacific Islanders (OR=0.84, 95%CI:0.78, 0.89) had lower odds of substance misuse. The multivariate model found an upward trend in the predicted probability of substance misuse by year and housing status. The predicted probability of substance misuse from 2013 to 2022 increased from 0.426 to 0.531 for privately housed service users, from 0.475 to .581 for institutionalized service users, and from 0.587 to 0.685 for unhoused service users.

Conclusions and Implications: The disproportionate percentage of unhoused people with substance misuse suggests the need to evaluate whether existing evidence-based interventions that are generally effective for promoting personality functioning and SUD recovery are scalable within publicly funded treatment settings. In addition to enhancing the capacity of the behavioral health workforce to meet the needs of unhoused people with PD, social policies to facilitate access to affordable housing and to retain people with psychiatric vulnerabilities in housing are necessary for reducing the social and individual burden of homelessness.