Depression, positive affect, and sexual behavior: a moderated mediation model of drug use among men who have sex with men in Hong Kong

Background: Drug use can be associated with poor mental health and risky sexual behaviors among men who have sex with men (MSM) and has become an important public health concern. The present study investigated the association between depression, positive and negative affect, number of sex partners, and drug use among MSM. Methods: A cross-sectional study was conducted among 420 MSM in Hong Kong. Participants completed a self-reported questionnaire that measured demographic characteristics, drug use, depression, sexual behaviors, and positive and negative affect. Hierarchical logistic regression was first conducted to examine the moderating role of the number of sex partners on the association between depression and drug use. A mediation model was then created to test the role of positive affect, negative affect and depression on drug use. A moderated mediation model was finally developed to test the overall associations. Results: After adjusting for significant demographic and other confounding factors, depression was positively associated with drug use (adjusted odds ratio [aOR] 1.05, 95 % confidence interval [CI] 1.02-1.09). The association between depression and drug use was positively moderated by number of sex partners. Positive affect significantly mediated the association between depression and drug use, exerting a negative indirect effect. Limitations: The casual inference was constrained by the cross-sectional design. Conclusions: Given the moderating role of the number of sex partners and the mediating role of positive affect on the association between depression and drug use, interventions to reduce drug use among MSM should aim to reduce risky sexual behaviors and promote mental health.