Sexual delay discounting as a moderator of the association between substance use and condomless anal sex among young black and Latino men who have sex with men.

In the United States, young men who have sex with men (MSM) remain one of the populations most disproportionately affected by human immunodeficiency virus (HIV) infection. According to surveillance data from the Centers for Disease Control and Prevention (), MSM accounted for 66% of newly diagnosed HIV cases nationwide, representing approximately 25,740 individuals. Among these, Black/African American and Hispanic/Latino MSM together comprised more than one-third of new diagnoses, with Black/African American MSM alone accounting for 38% (14,754 cases), indicating marked racial and ethnic disparities (). In addition, individuals aged 25–34 years represented the largest proportion of new HIV diagnoses (31.3%), suggesting that early adulthood remains a critical high-risk period for HIV infection (). Condomless anal sex (CAS) continues to be recognized as the primary route of HIV transmission among MSM (). Due to the fragility of rectal mucosal tissue, immunological susceptibility, and specific behavioral characteristics, the risk of HIV transmission through anal intercourse is substantially higher than that associated with heterosexual contact (). A substantial body of research has demonstrated that substance use, including alcohol consumption, illicit drug use, and misuse of prescription medications, is closely associated with sexual risk behavior and significantly increases the likelihood of HIV infection(; ; ). For instance, among MSM, individuals who engage in “chemsex” are more likely to have CAS and multiple sexual partners (). However, it is important to note that not all people who use substances exhibit sexual risk behavior. Systematic reviews have revealed considerable heterogeneity in the association between substance use and sexual risk behaviors, suggesting that personal traits may play a critical moderating role (). Consequently, researchers have begun to focus on the psychological mechanisms underlying sexual decision-making processes to better understand why substance use influences sexual risk behaviors differently across individuals (; ). The theory of delay discounting offers an important framework for understanding such individual differences (). This theory posits that when faced with choices between immediate and delayed rewards, individuals tend to devalue delayed rewards as the waiting time increases (). In other words, those who find it more difficult to wait for future outcomes exhibit a greater discounting of delayed rewards, reflecting a stronger present bias (). In the context of sexual behavior, this concept has been extended to sexual delay discounting (SDD), which assesses the tendency of individuals to choose between immediate unprotected sex and waiting to obtain a condom for protected sex (, ). By calculating the probability of choosing to wait under varying delay conditions, researchers can derive a discounting rate that reflects impulsiveness in sexual decision-making. A higher level of SDD reflects a stronger preference for immediate gratification and a greater propensity to engage in unprotected sex, whereas a lower level indicates greater self-control and a stronger inclination toward delayed gratification ().