All subcortical regions of interest identified in model 1 plus the right thalamus, the left and right putamen, the right globus pallidus, and the left nucleus accumbens had significantly lower volume in model 2 when alcohol-dependent participants were compared with nondependent control subjects. In addition, alcohol-dependent participants exhibited lower average thickness in 27 cortical regions of interest (Table 3, Figure 1). Cocaine dependence was associated with lower cortical thickness in only one brain region (see Table 3, Figure 1). No cross-validated differences in regional volume or thickness were significant for dependence on nicotine, methamphetamine, or cannabis on their own. Since most effects were related to alcohol dependence, a secondary linear contrast was performed to explore the effect of removing alcohol from the analysis. The contrast compared participants dependent on any substance except alcohol against nondependent control subjects. It revealed that the left inferior parietal cortex and the insula bilaterally were significantly thinner in dependent individuals (see Table 3).
