Background: Early initiation of alcohol or other substance use places adolescents at high risk for subsequent substance use disorders. Research on preventing substance use among Latino youth significantly lags behind the growth of this population.Objectives: To assess the effects of a family-based intervention on past 30-day substance use in a population of Latino early adolescents (ClinicalTrials.gov Identifier: NCT03642106).Methods: A first study followed a sample of 265 Latino adolescents (51% female) over 4 years (7th thru 10th grades) using an interrupted time series design to compare pre- to post-intervention trajectories. The second study compared post-trajectory slopes from the intervention group to a subsample of participants from the National Longitudinal Study of Youth (NLSY) who identified as Latino and were matched on age and gender. Both studies used a zero-inflated Poisson modeling approach.Results: A piecewise random intercept growth model showed non-significant differences between pre- to post-intervention trajectories for both the probability and frequency of alcohol (p = .30, .47) and tobacco use (p = .10, .37), and a significant increase in the probability of illegal drug use (p < .01) but not frequency (p = .65). The NLSY group significantly increased their probability of use across substances (all p < .01), and increased their frequency of use for alcohol (p < .05) and tobacco (p < .01).Conclusion: Longitudinal assessments comparing Latino youth to a non-equivalent control group indicate that strengthening family involvement in youths' schooling and promoting youth personal agency can prevent and/or reduce substance use during a developmental period in which use traditionally increases.
Keywords: Immigrant; Latino adolescent; Parental School Involvement; Prevention; alcohol tobacco and other drug use.