2.7 EPIGENETIC DETECTION OF TOBACCO AND CANNABIS SMOKING IN A LONGITUDINAL SAMPLE OF HIGH-RISK ADOLESCENTS IN EASTERN IOWA

Allan Andersen; Meg Gerrard; Robert A Philibert

doi:10.1016/j.jaac.2019.08.099

Objectives Early detection of tobacco and cannabis smoking in adolescents is critical to preventing progression to dependent use and other negative outcomes. Unfortunately, adolescent self-reporting of their substance-use habits is often inaccurate, leading to the window of interventions being missed. Methods The goal of the Healthier Tomorrow Study, a longitudinal study of eastern Iowa adolescents followed from 10 th to 12 th grades is to address the challenge of identifying nascent smoking behavior by characterizing epigenetic changes as adolescent smokers initiate and increase their use of tobacco and cannabis. In particular, we hypothesize that changes in methylation at the CpG cg05575921, a genomic methylation locus associated with smoke inhalation in over 50 epigenome-wide studies, may signal the initiation of smoking even at an early stage when use is irregular and may not be detected by conventional ELISA (enzyme-linked immunosorbent assay-based assays). Here, we present the results a preliminary analysis of 448 enrolled subjects at high risk because of having a friend or family member who smokes, of whom 387 have completed a 1-year follow-up visit and 252 have completed a 2-year follow-up visit. Results Study participants report high rates of ever using nicotine-containing products (25%), cannabis (28%), or both (17%) across the observation period. Strong inverse relationships are seen between cg05575921 methylation and both serum cotinine level ( p = 1.99e-68) and serum tetrahydrocannabinol ( p = 7.49e-24). Among adolescents with the greatest epigenetic evidence of smoke inhalation at study intake (n = 44), defined as those in the bottom 10 th percentile of methylation at cg05575921 (< 82.3%), there is a significantly increased probability of demonstrating serum cotinine values greater than 3 ng/mL (OR = 3.24, p < 0.01), serum THC values of greater than > 0.5 ng/mL (OR = 3.56, p < 0.01), or both (OR = 4.97, p < 0.001) during the observation period. In contrast, the probability of those in the bottom 10 th percentile of methylation admitting to any use of either cannabis or nicotine-containing products across the observation period is not significantly different ( p = 0.134) from those above the 10 th percentile. Conclusions Monitoring methylation at cg05575921 during late adolescence may improve the clinicians’ ability to identify nascent tobacco and cannabis smokers.

2.7 EPIGENETIC DETECTION OF TOBACCO AND CANNABIS SMOKING IN A LONGITUDINAL SAMPLE OF HIGH-RISK ADOLESCENTS IN EASTERN IOWA

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