Relationships between FA in regions that differed by group and measures of lifetime and recent (past 3 month) marijuana and alcohol use were examined among the two user groups (BG and BG+MJ, n = 28). As lifetime marijuana use increased, FA values in two left superior corona radiata clusters also increased (rs = .38 to .41, ps = .03). Further, more marijuana hits in the past three months was linked to higher FA in the superior longitudinal fasciculus (r = .51, p = .006). Similarly, those with more lifetime drinking occasions had higher FA in the superior longitudinal fasciculus (r = .43, p = .02). Lifetime drinking occasions and number of hits smoked in the past three months were not significantly correlated (p>.05). Alcohol drinks consumed in the past three months was not associated with FA in any of the 8 clusters that differed between groups.
