Socioecological Correlates of Substance Use Patterns Among Individuals with Serious Mental Illness: A Cluster Analytic Approach

Background/Purpose. Individuals with serious mental illness (SMI; e.g., schizophrenia, bipolar disorder, major depression) are at increased risk for substance misuse, which can worsen psychiatric symptoms, reduce treatment adherence, and lead to poorer health outcomes. Despite the prevalence of co-occurring SMI and substance use, few studies have explored the heterogeneity of substance use behaviors within this population. Also, limited research has examined how socioecological factors contribute to different patterns of substance use. Applying an ecological systems approach, the purpose of this study was to (1) identify distinct patterns of substance use among individuals with SMI receiving integrated primary and behavioral healthcare (PBHC) services, and to (2) examine how socioecological factors are associated with these substance use patterns.

Methods. This cross-sectional study used a sample of adults with SMI (N=1,257) receiving integrated PBHC services from public mental health agencies in the southern U.S. (age M=44.40 [range=18–83]; female=64.2%, male 35.8%; Black=49.5%, White=48.4%, other race=2.1%). A two-step cluster analysis identified distinct patterns of current substance use, including tobacco, alcohol, and illicit drugs (e.g., marijuana, cocaine, prescription stimulants, opioids). Four substance use clusters emerged: (1) high-risk tobacco users (n=367, 29.2%), (2) alcohol users (n=251, 20.0%), (3) illicit drug users with mixed polysubstance use (n=158, 12.6%), and (4) low-risk abstainers (n=454, 36.1%). A multinomial logistic regression was then conducted to examine socioecological factors associated with cluster membership, which was the dependent variable in this analysis. The independent variables were employment, living arrangement, family history of substance use, psychological distress (6 items; α=.87), functioning (8 items; α=.75), and social connectedness (4 items; α=.79). Age, gender, race, and education were control variables. All analyses were conducted using SPSS Version 28.

Results. Compared to low-risk abstainers (reference group), a family history of smoking significantly increased the likelihood of being in the high-risk tobacco group (OR=46.16, p<.001). For the alcohol users group, significant factors included living with others (OR=1.38, p=.04,), poorer functioning (OR=1.10, p=.01), family history of drinking (OR=15.89, p<.001), and family history of smoking (OR=31.89, p<.001). For the illicit drug users with mixed polysubstance use group, significant factors included family history of drinking (OR=4.52, p<.001), family history of smoking (OR=87.43, p<.001), being male (OR=1.83, p=.03), and being unemployed and looking for work (OR=19.79, p=.01).

Implications/Conclusions. Findings highlight the strong influence of family history on substance use patterns among individuals with SMI. A family history of smoking or drinking significantly increased the likelihood of being in all three substance use groups, indicating intergenerational risk, a finding consistent with the general population. Perceived poorer functioning and social factors, such as living arrangement and employment status, also notably contributed to the alcohol user and illicit drug user groups. These results emphasize the importance of integrated assessment and interventions that include routine screening for family substance use history, support for stable housing and employment, and services aimed at improving daily functioning for individuals with SMI.