Dissociating the effects of different substances, which are typically not used in isolation (especially by adolescents), has been a limitation of prior research with insufficient sample sizes. The large cohort to be recruited for the ABCD Study will enable sufficient power to capture and analyze different patterns of substance use along with many other variables of interest. The study will also be able to tell us about differences between early initiation (early teens) and later or no initiation; heavy vs. occasional use; and interactions between drugs, alcohol, and tobacco. Such a large sample, which includes 800 pairs of twins, will also allow researchers to tease out the effects of other variables such as genetics, socioeconomic status, social support systems, and other biological and behavioral factors associated with substance use, brain development, and other outcomes.
