Few studies have expanded on the macrostructural information provided by structural magnetic resonance imaging (MRI) in adolescent alcohol users. In addition to changes in overall white matter volume, the microstructural properties of white matter tissue at different stages of myelin development are important for the smooth, efficient, and integrated white matter fiber pathways necessary for neuronal transmission. Several studies have found differences in microstructural white matter indices of the corpus callosum between adolescents with and without alcohol use disorders [28,95], but less is known about white matter in adolescents who engage in sub-diagnostic drinking behaviors. Underage drinking is common [47], and most alcohol consumed by teens is in a binge or heavy episodic fashion. The National Institute on Alcohol Abuse and Alcoholism defines binge drinking as a pattern of alcohol consumption that brings blood alcohol concentration levels to .08 or above, which typically corresponds with consuming ≥ 5 drinks or ≥ 4 drinks on an occasion for boys and girls, respectively [66,88,106]. Sub-diagnostic binge drinking can be associated with changes in neurocognition and altered brain structure in youth and adults [41,48,56,77,98].
