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Updated: Aug 7, 2026

Brain Morphology of Cannabis Users With or Without Psychosis: A Pilot MRI Study
Published on: August 18, 2020
Cerebellar hypoactivity in frequent marijuana users
R I Block1, D S O'Leary, R D Hichwa
1Department of Anesthesia, University of Iowa, Iowa City 52242, USA.
Abstract:
It is uncertain whether frequent marijuana use adversely affects human brain function. Using PET, regional cerebral blood flow was compared in frequent marijuana users and comparable, non-using controls after at least 26 h of monitored abstention by all subjects. Marijuana users showed substantially lower brain blood flow than controls in a large region of posterior cerebellum, indicating altered brain function in frequent marijuana users. A cerebellar locus of some chronic and acute effects of marijuana is plausible, e.g. the cerebellum has been linked to an internal timing system, and alterations of time sense are common following marijuana smoking.
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