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Updated: Apr 20, 2026
Brain Morphology of Cannabis Users With or Without Psychosis: A Pilot MRI Study
Published on: August 18, 2020
Gross morphological brain changes with chronic, heavy cannabis use.
Valentina Lorenzetti1, Nadia Solowij1, Sarah Whittle1
1Valentina Lorenzetti, PhD, Monash Clinical and Imaging Neuroscience, School of Psychological Sciences, Monash University, and Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, and Melbourne Health, Melbourne, Victoria; Nadia Solowij, PhD, School of Psychology and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, and Schizophrenia Research Institute, Sydney, New South Wales; Sarah Whittle, PhD, Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, and Melbourne Health and Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Victoria; Alex Fornito, PhD, Monash Clinical and Imaging Neuroscience, School of Psychological Sciences, Monash University, and Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, and Melbourne Health, Melbourne, Victoria; Dan I. Lubman, PhD, FAChAM, FRANZCP, Turning Point, Eastern Health, and Monash University, Melbourne, Victoria; Christos Pantelis, MD, MRCPsych, FRANZCP, Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, and Melbourne Health, Melbourne, Victoria; Murat Yücel, PhD, MAPS, Monash Clinical and Imaging Neuroscience, School of Psychological Sciences, Monash University, and Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne, and Melbourne Health, Melbourne, Victoria, Australia.
Chronic heavy cannabis use was linked to smaller hippocampus and amygdala volumes in a unique study. This suggests a selective impact on brain morphology, particularly in the mediotemporal lobe.
Area of Science:
- Neuroimaging
- Neuroanatomy
- Substance Use Research
Background:
- Cannabis is widely used, but its long-term effects on brain structure remain incompletely understood.
- Previous research presents mixed findings regarding cannabis's impact on brain morphology.
- This study focuses on very heavy users with minimal confounding factors.
Purpose of the Study:
- To investigate the effects of chronic heavy cannabis use on the morphology of specific brain regions.
- To compare brain volumes between heavy cannabis users and non-using controls.
- To determine if cannabis use has a selective impact on brain structure.
Main Methods:
- Manual volumetric analysis of brain regions.
- Comparison of 15 very heavy cannabis users with 15 age- and IQ-matched controls.
- Exclusion of participants with significant psychiatric comorbidity or polysubstance use.
Main Results:
- Significantly smaller hippocampus volumes in heavy cannabis users compared to controls.
- Significantly smaller amygdala volumes in heavy cannabis users compared to controls.
- No significant differences in orbitofrontal cortex, anterior cingulate cortex, paracingulate cortex, or pituitary gland volumes.
Conclusions:
- Chronic heavy cannabis use selectively impacts mediotemporal lobe structures.
- The hippocampus and amygdala appear particularly vulnerable to the effects of long-term, heavy cannabis consumption.
- Findings suggest a detrimental morphological effect of cannabis on specific brain regions.
