Trends in Associations Between Substance Use and Suicidality and Patterns of Current Substance Use in U.S. Adolescents: A Repeated Cross-Sectional Study

INTRODUCTION: Substance use and suicidal thoughts and behaviors among U.S. adolescents are both major public health concerns. Despite extensive research establishing a link between substance use and suicidal thoughts and behaviors, little is known about how this relationship has evolved over time. Understanding the changes in these associations may illuminate factors driving the rise in adolescent suicidal thoughts and behaviors and guide public health interventions. METHODS: The 1991-2021 national survey data from the Youth Risk Behavior Surveillance System were analyzed. Race and ethnicity-specific changes in the associations between each of the 12 substance use variables and 4 suicidal thoughts and behaviors outcomes (suicidal ideation, suicide planning, suicide attempts, injurious suicide attempts) were assessed, by fitting logistic regression models with 3-way interactions between time, substance use, and race and ethnicity, while adjusting for age and sex and accounting for the complex survey design. Current (2017-2021) adolescent substance use patterns were then identified using an unsupervised clustering approach Uniform Manifold Approximation and Projection-Hierarchical Density-Based Spatial Clustering of Applications with Noise. RESULTS: Temporal trends varied by race and ethnicity for 36 of the 48 substance use and suicidal thoughts and behaviors combinations. Electronic vaping was unique in its nondecreasing association with all suicidal thoughts and behaviors measures across all racial and ethnic groups (slopes [annual log-odds change] varied between 0.03 and 0.36). Although cigarette use showed declining associations with suicidal thoughts and behaviors among White adolescents, alcohol, heroin, injected drug, and methamphetamine use showed divergent trends across racial and ethnic groups. Clustering analysis identified 5 substance use behavioral phenotypes, including nonusers (45.51%), poly- or illicit- users (20.84%), and other specific usage patterns (33.65%), with poly- or illicit- users reporting the highest rates of suicidal thoughts and behaviors (31% suicidal ideation, 26% suicide planning, 16% suicide attempts, 6.3% injurious suicide attempts). CONCLUSIONS: The finding that electronic vaping consistently showed an increasing association with all suicidal thoughts and behaviors measures highlight the urgency of implementing suicide prevention programs targeting adolescents who vape. Future research is needed to unveil the specific substance or combination of substances that contribute to the elevated risk of suicidal thoughts and behaviors among poly- or illicit- users.