Developmental changes in the effects of substance use on HIV risk in young MSM: A longitudinal dyadic model

Men who have sex with men (MSM) account for more than half of all new HIV/AIDS diagnoses in the US each year, and young MSM have the highest increases in new infections. Positive associations have consistently been found between the use of certain drugs and sexual risk, but research on alcohol use as a predictor of risk has been less consistent and possibly developmentally dependent; there has been very limited developmental research in this area. A sample of 117 young MSM (ages 16–20 at baseline) was recruited using a modified form of respondent drive sampling. The cohort is primarily racial/ethnic minority young men (74%). At each of 5 assessments over 2.5 years, participants reported on characteristics of up to 3 sexual partners (total of 573 partnerships), including number of unprotected sex acts and use of alcohol and drug prior to sex. Hierarchical linear modeling (HLM) was used to study developmental changes in the effects of alcohol and drug use on rates of unprotected sex. Rates of unprotected sex changed considerably across relationships, rather than being stable in the same participant over time (ICC = 13%). The effects of alcohol were developmentally dependent (p < .01), with frequency of consumption decreasing rates of unprotected sex at younger ages, but at age 21 effect shifted to increase risk. Drug use had a larger effect on unprotected sex than alcohol use (p < .01), but its effects did not change across development. Implications for future research and behavioral interventions are discussed.