The current study adds to this literature by prospectively examining the effects of alcohol use initiation on ongoing structural brain development in a typically developing low-risk sample of adolescents without histories of externalizing behavior or other psychopathology, without concomitant use of other substances, and – most notably – without substance exposure at the baseline assessment. Across a two-year follow-up interval, participants who transitioned into alcohol use were compared to those who did not. Based on the fact that alcohol use generally begins after age-related declines in cortical gray matter have stabilized (15,16), we hypothesized that we would not observe altered patterns of cortical thickness in alcohol initiators versus non-users. Differences, if observed, would likely be limited to anterior brain regions given that these are among the last to reach maturational plateaus (15,16). Rather, we expected to observe deviations in white matter development within alcohol initiators, particularly in subcortical regions involved in reward processing (e.g. ventral striatum) and executive functions (e.g. dorsal striatum; thalamus) as well as areas and tracts such as the superior longitudinal fasciculus and cingulate cortex, that interconnect higher frontal regions with other cortical and subcortical regions.
