Anterior cingulate grey-matter deficits and cannabis use in first-episode schizophrenia.

Background: Despite the high prevalence of cannabis use in schizophrenia, few studies have examined the potential relationship between cannabis exposure and brain structural abnormalities in schizophrenia.
Aims: To investigate prefrontal grey and white matter regions in patients experiencing a first episode of schizophrenia with an additional diagnosis of cannabis use or dependence (n=20) compared with similar patients with no cannabis use (n=31) and healthy volunteers (n=56).
Method: Volumes of the superior frontal gyrus, anterior cingulate gyrus and orbital frontal lobe were outlined manually from contiguous magnetic resonance images and automatically segmented into grey and white matter.
Results: Patients who used cannabis had less anterior cingulate grey matter compared with both patients who did not use cannabis and healthy volunteers.
Conclusions: A defect in the anterior cingulate is associated with a history of cannabis use among patients experiencing a first episode of schizophrenia and could have a role in poor decision-making and in choosing more risky outcomes.