A national longitudinal study of sexual orientation discordance, sexual identity fluidity, and alcohol and other drug use disorder symptoms.

Background: Many national studies fail to account for discordance between sexual orientation dimensions (e.g. a mismatch between sexual identity and sexual attraction) or sexual identity fluidity (e.g. changes in sexual identity over time). Objective: To examine the longitudinal relationships among sexual identity fluidity/stability, sexual orientation discordance/concordance, and alcohol and other drug use disorder symptoms. Methods: The study used nationally representative longitudinal data from Waves 1-5 (2013-2019) of the Population Assessment of Tobacco and Health (PATH) study of US adolescents and adults ( N = 24,591). Results: Substance use disorder symptoms were most prevalent (45.8%) among bisexual-stable females relative to all other sexual identity subgroups. The adjusted odds ratios (AORs) of substance use disorder symptoms were significantly higher among bisexual-stable females vs. heterosexual-stable females in all models (AOR range: 1.94-2.32), while no such associations were found for males. Sexual identity-attraction discordant females had significantly greater AORs (17/20 instances) of substance use disorder symptoms compared to concordant females; this finding was not as consistent for males (6/20 instances). Conclusion: Sexual orientation discordance was significantly associated with substance use disorder symptoms, especially among females discordant in their sexual identity and attraction. Bisexual-stable and discordant females are at highest risk of developing symptomatic substance use; it is vital that they receive screening, no matter where they are in their coming out process. This study highlights pitfalls of relying solely on cross-sectional data using a single sexual orientation dimension to understand the relationship between sexual orientation and substance use disorder.