Alcohol’s negative effects on brain structure are perhaps not surprising as a consequence of prenatal exposure, because this is a recognized time of rapid neurodevelopment. Similarly, alcohol’s acceleration of normative age-based declines in neuronal volume is understandable, particularly in the context of alcohol dependence and associated nutritional compromise. Whether alcohol exerts deleterious effects during other periods of the lifespan that are similarly characterized by marked organizational changes in brain structure is unknown. Adolescence represents one such period (14). Studies of brain structure during adolescence have revealed normative patterns of decrease in gray matter volume, particularly in cortical regions (15,16), as well as linear increases in white matter volume (17) throughout the brain (but see (18) for a contrary pattern of findings where white matter volumes were observed to decrease in the prefrontal cortex, particularly in females, in late adolescence). Diffusion tensor imaging (DTI) studies suggest that white matter becomes increasingly well-organized during adolescence (19-21) and that functional connectivity across cortical-to-subcortical circuits becomes more efficient (22).
