Overall, we found that teens reporting histories of binge drinking alone and with concomitant marijuana use displayed lower FA compared to controls. Teens reporting binge drinking behaviors alone had significantly lower FA than controls in all eight clusters, whereas teens reporting both binge drinking and marijuana use had lower FA than controls in only three of the eight clusters: two clusters located in the corona radiata and one cluster in the inferior longitudinal fasciculus. In seven clusters (excluding the right inferior longitudinal fasciculus), teens reporting both marijuana and binge drinking had higher FA values than teens who reported binge drinking only (statistically significant in four of the eight clusters: corona radiata, fronto-occipital fasciculus, middle cerebellar peduncle, superior longitudinal fasciculus).
