“Substance use may confound the study of brain structure in schizophrenia. We used voxel-based morphometry (VBM) to examine whether differences in regional gray matter volumes exist between schizophrenia patients with (n = 92) and without (n = 66) clinically significant cannabis and/or alcohol use histories compared to 88 healthy control subjects.

Relative to controls, patients with schizophrenia had reduced gray matter volume in the bilateral precentral gyrus, right medial frontal cortex, right visual cortex, right occipital pole, right thalamus, bilateral amygdala, and bilateral cerebellum regardless of substance use history.

Within these regions, we found no volume differences between patients with schizophrenia and a history of cannabis and/or alcohol compared to patients with schizophrenia without a clinically significant substance use history.

Our data support the idea that a clinically meaningful history of alcohol or cannabis use does not significantly compound the gray matter deficits associated with schizophrenia.”