The Effects of Alcohol Intoxication on Sexual Risk Behavior in Men Who Have Sex with Men: Considering PrEP, HIV Viral Load, and Inhibition Conflict

Experimental research has shown consistent evidence for a causal effect of alcohol on sexual risk behavior relevant to HIV. However, event-level research has produced mixed results. Limited research has assessed alcohol and sexual risk in the context of pre-exposure prophylaxis (PrEP) and treatment as prevention (TasP; i.e., maintaining an undetectable HIV viral load). The present study explores the event-level relationship between alcohol use and sexual risk behavior in a cross-sectional sample of men who have sex with men (MSM; N = 464). Event-level data from N = 1,049 retrospectively reported sexual encounters were analyzed using a series of generalized hierarchical linear regressions. Alcohol intoxication showed inconsistent associations with sexual risk behaviors in the full sample, but PrEP and TasP significantly moderated these associations. Participants who did not use PrEP or did not currently have an undetectable viral load (n = 217) showed a positive association between alcohol intoxication and sexual risk behavior, while those using PrEP or reporting an undetectable viral load (n = 247) showed no association. Moderating effects remained significant when accounting for participants' self-reported level of concern about HIV and STI transmission. These results highlight how alcohol's disinhibiting effects on sexual risk behavior may be primarily relevant for those at greatest risk for HIV transmission. Results are discussed in the context of the inhibition conflict model of Alcohol Myopia Theory and HIV epidemiology.