The Effect of Momentary Affect on Substance Use among Young Adults Who Experience Homelessness.

IntroductionLittle is known about the momentary patterns and predictors of substance use among young adults who experience homelessness. To enhance understanding of substance use patterns, smartphone-based ecological momentary assessment (EMA) was utilized to examine the real-time association between affect and substance use. Methods: 251 young adults (aged 18-27) with history of homelessness were recruited from supportive housing programs and drop-in facilities in Los Angeles. Exploratory factor analysis was used to examine the latent structure of positive and negative affective states and mixed-effects logistic regression models were completed separately for both the full remaining sample (n = 227) and a subsample of alcohol or cannabis users (n = 145) to evaluate whether positive or negative affect predicted lead, recent, or lagged substance use. Results: Greater positive affect within-person was associated with greater odds of alcohol or cannabis use within the past two hours, and participants who reported feeling more negative than their peers experienced greater odds of reporting use within the past 4 h and the following two hours. Conclusion: Results suggest that individuals experience a heightened positive mood compared to their own average mood, concurrently or immediately after engaging in alcohol or cannabis use. Heightened positive mood might be an anticipatory effect of drinking or cannabis use. Future research should consider a longer study period to capture multiple drinking or drug use events over a longer period and consider more environmental exposures that may influence the frequency or intensity of substance use.