MANCOVA with BMI as covariate revealed a significant main effect of BMI [F(2,80) = 3.1, p = 0.020] and group [F(2, 80) = 3.58, p = 0.001] for WM volumes. Significant group effects were observed for total WM and all lobar WM volumes except oWM: total WM [F(2, 82) = 9.93, p < 0.001], fWM [F(2, 82) = 7.38, p = 0.001], pWM [F(2, 82) = 9.99, p < 0.001], and tWM [F(2, 82) = 6.19, p = 0.003]. Pairwise comparisons showed PSU with significantly larger WM volumes than ALC for all four lobes and with significantly larger fWM and pWM than LD. ALC showed WM volumes similar to LD in all lobes except the temporal lobe, where ALC had less WM than LD. Of all lobar WM volumes, pWM volume in PSU correlated positively with average amount of cocaine used over the year prior to the study (r = 0.55, p = 0.044, uncorrected).
