In a preliminary analysis, we looked at the effects of both binge drinking alone and with combined marijuana use on white matter integrity 44. Forty-two participants (ages 16–19) were identified as controls (n= 14), binge drinkers (≥ 4 drinks on an occasion for females, ≥ 5 drinks on an occasion for males; n= 14), or binge drink+marijuana users (n= 14). Adolescent participants received DTI with whole brain coverage. Diffusion weighted data were collected on a 3-Tesla GE magnetic resonance scanner (repetition time=12000 ms; echo time=93.4 ms; 36 × 3.0 mm thick axial slices; voxel resolution 1.875 × 1.875 × 3.0 mm3 , b-value = 2000 s/mm2). Diffusion-weighted images were acquired in 15 directions, in addition to a normalization image (b=0) with no diffusion encoding 45. Four volumes were acquired and averaged for each direction and the b = 0 volume. FA (or MD) maps from each participant were submitted to Tract-Based Spatial Statistics (TBSS 46), which facilitated voxelwise between-group comparisons.
