Anxiety as a predictor of the age of initiation of tobacco and cannabis use in adolescents and young adults

Background: Previous research has shown important links between anxiety and the use of tobacco and cannabis. However, it remains unclear whether anxiety leads youth to start using tobacco and cannabis at an earlier age. Methods: Data were drawn from Texas Adolescent Tobacco and Marketing Surveillance System for the years 2019-2021(Waves 9-14). Participants were in 10th-grade, 12th-grade, and two years post-high school at baseline. The outcomes were the age of first use of cigarettes, e-cigarettes, and cannabis. Interval-censoring Cox proportional hazards models were fit to examine the differences in the estimated age of initiation of tobacco and cannabis use by anxiety. Results: Among the 10th-grade cohort, participants with anxiety had an increased risk of an earlier age of cigarette [AHR = 2.29(1.63-3.23)], e-cigarette [AHR = 1.53 (1.17-2.00)], and cannabis [AHR = 1.59(1.23-2.05)] initiation. Among the 12th-grade cohort, participants with anxiety had an increased risk of an earlier age of cigarette [AHR = 1.52(1.21-1.90), e-cigarette [1.25(1.01-1.60)] and cannabis [AHR = 1.35(1.09-1.67] initiation. Among the post-high school cohort, the only significant association found was for cannabis initiation [AHR = 1.33(1.11-1.58). Between ages 18-to-19 years in the 10th-grade cohort, and between ages 20-21 years in the 12th-grade cohort, cumulative incidence of each of the three outcomes initiation doubled among anxious youth. Conclusions: This study's findings show that anxiety symptoms can increase the risk of substance use initiation at an earlier age, especially among the youngest adolescent cohort (similar to 15-to-16-year-olds). These findings highlight the importance of early screening and treatment of anxiety symptoms as a preventive measure to delay or prevent the onset of substance use initiation.