as “typical” for the United States adolescent population. As suggested here by emerging differences in self-reported behavioral control over time in alcohol use initiators, those impacts are likely to be neurodevelopmental but also behavioral. Behavioral effects associated with subclinical patterns of substance use are often subtle in late adolescence or young adulthood, because these periods are recognized as times of relatively enhanced cognitive reserve. Future analyses will examine microstructural properties of white matter in more detail to assess the impact of alcohol use on myelination. Although we did not find differences between groups in radial versus axial diffusivity, we expect that such differences may emerge with continued follow-up of alcohol users. Thus, an ongoing goal of our work is to characterize longer-term neurocognitive and affective development as a function of the timing of alcohol use initiation in adolescence.
