Separating the Association Between Inhibitory Control and Substance Use Prevalence Versus Quantity During Adolescence: A Hurdle Mixed-Effects Model Approach.

Background: Inhibitory control is a critical component to the self-regulation of affect and behavior. Research consistently demonstrates negative associations between inhibitory control and several problem behaviors including substance misuse during early adolescence. However, analytic approaches previously used have often applied ordinary least squares (OLS) regression to non-normal count data with an excessive number of zeros (i.e., never users), violating several model assumptions. Further, OLS regression fails to model effects of the independent variable, separately, for both prevalence and quantity of use. Objective: The study objective was to simultaneously model associations between inhibitory control and both past 30-day prevalence and amount of cigarette and marijuana use. It was hypothesized that when doing so, inhibitory control would be significantly associated with prevalence, but not quantity of use. Method: Hurdle Mixed-effects Models (HMM) were used for hypothesis testing on data collected from 3,383, 9th grade adolescents (Mage = 14.08 years). Results: Results confirmed hypotheses, demonstrating that although significant bivariate associations between inhibitory control and quantity of cigarette and marijuana use existed, HMM analyses established that the associations were more precisely specific to past 30-day prevalence, and not quantity of use. Conclusion: Results from a HMM approach contribute to a more comprehensive and nuanced understanding of which characteristics of cigarette and marijuana use are associated with inhibitory control during early adolescence. [ABSTRACT FROM AUTHOR]