Increased gray matter density in patients with schizophrenia and cannabis use: A voxel-based morphometric study using DARTEL

Alterations in gray matter density as well as cognitive impairments are commonly described in patients with schizophrenia (SCH patients). Both gray matter deficits and cognitive impairments have recently been discussed to represent vulnerability markers of schizophrenia. The counterintuitive finding of better cognitive performance in patients with schizophrenia and cannabis use (SCH + CAN patients) compared to cannabis naïve patients is discussed as a reflection of lower vulnerability for schizophrenia in at least one subgroup of SCH + CAN patients. We hypothesized that SCH + CAN patients would display fewer gray matter deficits compared to SCH patients reflecting their presumed lower vulnerability. We therefore compared gray matter density in 30 first episode SCH + CAN and 24 first episode SCH patients using a fast diffeomorphic registration algorithm (DARTEL) and voxel-based morphometry (VBM). We found less severe cognitive impairments and middle frontal gray matter deficits in the SCH + CAN patients. In the pooled sample gray matter density was positively associated with cognitive functioning. Results may support the hypothesis of a lower biological vulnerability in at least one subgroup of SCH + CAN patients.