Structural MRI Findings in Long-Term Cannabis Users: What Do We Know?

  title={Structural MRI Findings in Long-Term Cannabis Users: What Do We Know?},
  author={Valentina Lorenzetti and Daniel I Lubman and Sarah Whittle and Nadia Solowij and Murat Y{\"u}cel},
  journal={Substance Use \& Misuse},
  pages={1787 - 1808}
In animal studies, tetrahydrocannabinol (THC) has been found to affect brain morphology, particularly within areas rich in cannabinoid receptors (e.g., hippocampus, cerebral cortex). While cannabis remains the most widely used illicit drug worldwide, there has been limited work investigating its effects on human brain tissue. In this paper, we conducted a systematic review of existing structural magnetic resonance imaging studies to examine whether cannabis use is associated with significant… 
Long-Term Effects of Cannabis on Brain Structure
Evidence is provided that regular cannabis use is associated with gray matter volume reduction in the medial temporal cortex, temporal pole, parahippocampal gyrus, insula, and orbitofrontal cortex; these regions are rich in cannabinoid CB1 receptors and functionally associated with motivational, emotional, and affective processing.
Structural and Functional Imaging Studies in Chronic Cannabis Users: A Systematic Review of Adolescent and Adult Findings
Chronic cannabis use may alter brain structure and function in adult and adolescent population and functional neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum.
Effects of regular cannabis use on neurocognition, brain structure, and function: a systematic review of findings in adults
It is suggested that regular cannabis use is associated with mild cognitive changes in addition to structural and functional alterations in the brain in adults, and the morphological alterations could ultimately affect brain organization and function.
Cannabis Use And Brain Volumes: A Co-Twin Control Analysis
A large number of studies have used structural magnetic resonance imaging (sMRI) as an imaging technique, and have found that regular cannabis use is associated with alterations in certain brain regions (Lorenzetti et al., 2014).
Cognition and cannabis: from anecdote to advanced technology.
  • J. Brust
  • Biology, Psychology
    Brain : a journal of neurology
  • 2012
A novel strategy is applied—diffusion-weighted MRI and connectivity mapping—to demonstrate microstructural alterations affecting brain axonal pathways in long-term cannabis users, consistent with the endocannabinoid system playing a key role in brain development.
Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings
To address the question whether impulsivity as a trait precedes cannabis consumption or whether cannabis aggravates impulsivity and discontinuation of usage more longitudinal study designs are warranted.
Grey Matter Changes Associated with Heavy Cannabis Use: A Longitudinal sMRI Study
Results suggests that small GM volumes in the medial temporal lobe are a risk factor for heavy cannabis use or that the effect of cannabis on GM reductions is limited to adolescence with no further damage of continued use after early adulthood.
Larger Gray Matter Volume in the Basal Ganglia of Heavy Cannabis Users Detected by Voxel-Based Morphometry and Subcortical Volumetric Analysis
This study does not support previous findings of hippocampal and/or amygdala structural changes in long-term, heavy cannabis users, but does provide evidence of basal ganglia volume increases.
The association between regular cannabis exposure and alterations of human brain morphology: an updated review of the literature.
The notion that regular cannabis use is associated with alterations of brain morphology is supported, and the need to consider particular methodological issues when planning future cannabis research is highlighted.
Effect of long-term cannabis use on axonal fibre connectivity.
The findings indicate long-term cannabis use is hazardous to the white matter of the developing brain and delaying the age at which regular use begins may minimize the severity of microstructural impairment.


Functional Imaging Studies in Cannabis Users
  • Linda Chang, E. Chronicle
  • Biology, Psychology
    The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry
  • 2007
Although there is only equivocal evidence that chronic cannabis use might result in structural brain changes, blood-oxygenation-level-dependent-fMRI studies in chronic users consistently show alterations, or neuroadaptation, in the activation of brain networks responsible for higher cognitive functions.
Regional brain abnormalities associated with long-term heavy cannabis use.
These findings indicate that heavy daily cannabis use across protracted periods exerts harmful effects on brain tissue and mental health.
Lack of hippocampal volume change in long-term heavy cannabis users.
Investigating the effects of cannabis smoking on the morphology of the hippocampus in older, long-term cannabis users found no significant adjusted differences in volumes of gray matter, white matter, cerebrospinal fluid, or left and right hippocampus.
A preliminary DTI study showing no brain structural change associated with adolescent cannabis use
It is concluded that frequent cannabis use is unlikely to be neurotoxic to the normal developing adolescent brain.
Effects of frequent cannabis use on hippocampal activity during an associative memory task
Brain neuroimaging in cannabis use: a review.
Structural abnormalities generally have not been identified with chronic use and regular users demonstrate reciprocal changes in brain activity globally and in cerebellar and frontal regions, but generalization is limited by the lack of use of diagnostic criteria, appropriately paired neuropsychological testing or means to better quantify cannabis use and abstinence.
Spatial working memory in heavy cannabis users: a functional magnetic resonance imaging study
Recent cannabis users displayed greater and more widespread brain activation than normal subjects when attempting to perform a spatial working memory task, which suggests that recent cannabis users may experience subtle neurophysiological deficits, and that they compensate for these deficits by “working harder”—calling upon additional brain regions to meet the demands of the task.
Altered brain tissue composition in heavy marijuana users.
The chronic effects of cannabis on memory in humans: a review.
The impact of not only specific parameters of cannabis use in the manifestation of memory dysfunction, but also such factors as age, neurodevelopmental stage, IQ, gender, various vulnerabilities and other substance-use interactions are considered, in the context of neural efficiency and compensatory mechanisms.
Dorsolateral Prefrontal Cortex N-Acetylaspartate/Total Creatine (NAA/tCr) Loss in Male Recreational Cannabis Users