hits per month in the past 3 months (r = -0.35, P = 0.039) and fewer days since last alcohol use (r = 0.76, P = 0.03). For particularly heavy users (lifetime marijuana use ≥ 350 and lifetime alcohol drinks ≥165; n = 9), splenium FA negatively correlated with lifetime marijuana use (r = -0.67, P = 0.04), and FA in the anterior limb of the internal capsule (where users had higher FA than controls) positively correlated with lifetime alcohol use (r = 0.67, P = 0.04). Mean FA and MD did not relate to estimated premorbid IQ in either group, and no gender main effects or gender by group interactions were seen.
