Does Exposure to Abstinence and Zero Tolerance Drug and Alcohol Policies in Adolescence Predict Young Adult Abstinence?

Introduction: The International Youth Development Study (IYDS) is a longitudinal study initiated in 2002 that cross-nationally compared adolescent development characteristics and the associated effects of alcohol and drug policies in matched state-representative samples in Washington State (WA) and Victoria, Australia (VIC). Prior IYDS studies examining school drug policies have shown that abstinence and zero-tolerance approaches were adopted by schools in WA while harm-minimisation strategies were adopted by VIC schools, based on school administrator and student report surveys. In adolescence (ages 11 to 17 in surveys from 2002 to 2004), higher rates of illicit drug use but also abstinence from alcohol and other drug use were found in WA compared to VIC; whereas higher rates of alcohol and tobacco use were found in VIC compared to WA. The 2014 IYDS follow-up (87% of initial sample retained, N=1,601 available for the present analysis) permitted cross-national comparison of whether state differences in alcohol and drug use patterns were maintained at average age 25.    

Methods: Latent Profile Analysis (LPA) was used to identify young adult drug use patterns at age 25. Measures including alcohol, marijuana, tobacco, stimulants, ecstasy, and over-the-counter-drug in the past month and past year were used to inform the drug use patterns.

Results: Preliminary results showed that a 4-latent-class model and a 5-latent-class model was best fit to the WA sample (N=805) and the Victorian sample (N=796) respectively. Similar latent classes identified in both states were the “Abstinent - Non users” (38.5% in WA vs. 28.8% in VIC) and the “Heavy alcohol users” (40.5% in WA vs. 39.3% in VIC) latent classes. Varied patterns of poly-drug use were less evident in WA (21.0%) compared to VIC (31.8%). Two different poly-drug use latent classes were identified in WA: the “All drugs except stimulants and ecstasy” (18.4%) and the “Marijuana and multi-drug users” (no alcohol, cocaine, and ecstasy use; 2.6%) latent classes. In contrast, in VIC, three different poly drug use latent classes emerged: the “Alcohol, marijuana, and tobacco users” (13.1%), the “All-drug users” (14.9%), and the “Marijuana and tobacco users” (3.8%) latent classes. Predictors of environmental influences will be entered into the models.

Conclusions: Preliminary findings support the view that youth exposed to adolescent abstinence policies in WA maintained significantly higher rates of abstinence as young adults. The VIC adolescents exposed to harm-minimisation had higher rates of poly drug use as young adults. Significant predictors of these drug use profiles will be presented. Findings will be discussed in relation to the alcohol and drug use policies in the two states.