Longitudinal Associations between Homelessness and Substance Use: Investigating Demographic Differences for Young Adults in Treatment.

To examine prospective, bidirectional associations between homelessness and substance use frequency among young adults receiving substance use treatment in the United States. We also investigated potential differences across demographic subgroups. Young adults ( = 3717, age = 20.1, 28% female, 7.3% sexual/gender minority, and 37% non-Hispanic White) receiving substance use treatment in the U.S. completed assessments at intake, 3 months, 6 months, and 12 months post-intake. Latent growth curve models with structured residuals (LGC-SR) were used to examine cross-lagged associations between homeless days and frequency of substance use and associated problems. Models were stratified by sex, race/ethnicity, and sexual and/or gender minority status. Overall, days spent homeless ( -0.19,  = 0.046) and substance use frequency ( -6.19,  < 0.001) significantly decreased during treatment, with no significant cross-lagged associations between homeless days and substance use frequency. However, results differed by race and ethnicity. For non-Hispanic White young adults, greater substance use at treatment entry was associated with steeper declines in homeless days between-persons ( = -0.14,  = 0.04). For African Americans, homeless days at treatment entry were associated with greater increases in substance use between-persons ( = 0.29,  = 0.04). No significant differences were found by sex or sexual/gender minority status. Despite overall declines in homelessness and substance use during treatment, these outcomes may unfold differently for non-Hispanic White and African American young adults. More support may be needed for African American young adults reporting homelessness at treatment entry.