(HealthDay News) – A history of marijuana use is associated with changes in brain morphology and poorer working memory both in healthy people and particularly in patients with schizophrenia, according to a study published online Dec. 15 in the Schizophrenia Bulletin.

Matthew J. Smith, PhD, from the Northwestern University Feinberg School of Medicine in Chicago, and colleagues performed large-deformation high-dimensional brain mapping with magnetic resonance imaging to generate surface maps in 44 healthy people, 10 people with a history of cannabis use disorder (CUD), 28 schizophrenia patients with no history of CUD, and 15 schizophrenia patients with a history of CUD. Differences in brain morphology were correlated with working memory and CUD history.

The researchers found similar differences in brain morphology in the striatum, globus pallidus, and thalamus associated with cannabis use in both healthy people and schizophrenia patients. In both groups, cannabis-associated differences in the shape of the striatum and thalamus correlated with poorer working memory and the development of CUD at a younger age. Cannabis-based differences were found to be consistent and exaggerated in patients with schizophrenia compared with healthy people.

“The cross-sectional results suggest that both CUD groups were characterized by working memory deficits and subcortical neuroanatomical differences,” Smith and colleagues conclude.

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