Vulnerability to Substance Use: Transitions and Trajectories in ABCD Youth with Validation Using Longitudinal Twin Family Samples - Adolescence is a key developmental stage during which many youth experiment with substances (e.g., alcohol, nicotine, cannabis). Some experimenters progress to regular use, potentially leading to substance use disorders. Whether and how early youth initiate substance use (SU) and how quickly they transition to heavier use is influenced by demographic, environmental, and genetic factors. Internalizing (INT) and externalizing (EXT) behaviors, sensitivity to reward, and cognitive control/impulsivity have all been associated with SU trajectories. However, questions remain about whether these associations are causal or reflect shared risk factors, whether INT behaviors are risk or protective factors, and whether INT/EXT effects are interactive. Changes in reward sensitivity and development of cognitive control across adolescence may further impact SU trajectories and may moderate the role of INT/EXT on SU. Data from longitudinal twin studies also suggest a change in the relative importance of environmental and genetic factors on individual differences in both SU and behavioral correlates, with family environment more critical in early adolescence and genetic factors increasing in importance with age. However, few studies have large enough samples that are epidemiologically informed by the US population in terms of sex, race/ethnicity and socio-economic status and are genetically informative, with assessments of key domains across this critical developmental period. The nationwide Adolescent Brain Cognitive Development (ABCD) Study, which assesses youth (N=11k+) from age 9-10 until young adulthood, provides a unique opportunity to investigate the role of demographic, environmental, and psychological factors in the rate of transition from substance initiation to regular and/or heavy use, controlling for potential confounding by genetic factors to inform when prevention might be most successful. The ABCD sample was enriched with >1000 twin pairs, primarily collected at four sites with long histories of twin research (Minnesota, Colorado, Missouri, & Virginia), and including siblings and twins recruited at other sites. This unique genetically informative subsample, especially when analyzed jointly with the remaining population-based sample on whom genomic data and a rich set of sociodemographic and environmental variables are available, affords great opportunities. We have assembled investigators from the four twin sites, who each bring unique expertise and rigor in assessment and genetic epidemiological methods. Their skills are relevant to the study of SU trajectories and the simultaneous changes in EXT/INT behavior and reward sensitivity/cognitive control. In addition, each site has existing twin family data from longitudinal assessments of SU and its correlates, which serve as validation samples to test assumptions used in ABCD analyses and validate conclusions drawn from ABCD analyses. Our team of investigators already has a track record of collaboration including publications as well as curation of an online resource. We have three aims:
