Structural MRI findings in long-term cannabis users: what do we know?
Valentina Lorenzetti, Dan I Lubman, Sarah Whittle, Nadia Solowij, Murat Yücel
Substance Use & Misuse September 2010 DOI: 10.3109/10826084.2010.482443 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Systematic review Peer reviewed |
|---|---|
| Population | Cannabis users, in structural neuroimaging studies with diverse sample characteristics such as age and duration and frequency of use |
| Topics | Cannabis |
| Key findings | Across 13 structural MRI studies, no study found global structural brain changes in cannabis users, while six reported regional alterations, most frequently in the hippocampus and parahippocampus, with inconsistent findings across studies. The authors suggest THC exposure affects brain morphology, especially in medial-temporal regions, and that regional changes are associated with cumulative dosage, frequency of use, and measures of depressive and psychotic symptoms. |
Abstract
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 changes in brain anatomy. We identified only 13 structural neuroimaging studies, which were diverse in terms of sample characteristics (e.g., age of participants, duration and frequency of use) and methodology (e.g., image analysis). No study found global structural changes in cannabis users, although six studies reported regional alterations. While changes in the hippocampus and parahippocampus were frequently identified, the findings were inconsistent across studies. The available literature also provides some evidence that regional structural changes are associated with cannabis use patterns (particularly cumulative dosage and frequency of use), as well as measures of psychopathology (e.g., measures of depressive and psychotic symptoms). Together, these structural imaging findings suggest that THC exposure does affect brain morphology, especially in medial-temporal regions. Given the small literature available and the limitations of studies to date, further research is clearly required, particularly given the prevalence of cannabis use worldwide.
Comparable studies
Other systematic reviews and meta-analyses on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Effects of cannabis use on outcomes of psychotic disorders: systematic review People with psychotic disorders, as examined in 13 longitudinal studies | 2008 | Systematic review | |
| The Impact of Cannabis Use on Cognitive Functioning in Patients With Schizophrenia: A Meta-analysis of Existing Findings and New Data in a First-Episode Sample Patients with established schizophrenia (meta-analysis: 572) and patients with... | 2010 | Meta-analysis and cross-sectional observational study | n = 700 |
| Medicinal cannabis for psychiatric disorders: a clinically-focused systematic review | 2020 | Systematic review | |
| Neuroimaging in cannabis use: a systematic review of the literature Cannabis users and controls in neuroimaging studies | 2009 | Systematic review | |
| Human Laboratory Studies on Cannabinoids and Psychosis. Healthy human subjects and individuals with schizophrenia | 2016 | Systematic review |
Citations in the library
Cited by 22
- The neuropsychopharmacology of cannabis: A review of human imaging studies Pharmacology & Therapeutics October 20, 2018
- Grey Matter Volume Differences Associated with Extremely Low Levels of Cannabis Use in Adolescence Journal of Neuroscience January 14, 2019
- Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings Current Pharmaceutical Design May 10, 2014
- Cannabis affects people differently: inter-subject variation in the psychotogenic effects of Δ9-tetrahydrocannabinol: a functional magnetic resonance imaging study with healthy volunteers Psychological Medicine October 1, 2012
- Association between age of cannabis initiation and gray matter covariance networks in recent onset psychosis Neuropsychopharmacology March 3, 2021
and 17 more in the library
Cites 10
- Psychiatric effects of cannabis The British Journal of Psychiatry February 1, 2001
- The effect of cannabis on the brain: can it cause brain anomalies that lead to increased risk for schizophrenia? Current Opinion in Psychiatry March 1, 2008
- Functional imaging studies in cannabis users. The Neuroscientist October 2007
- Dorsolateral prefrontal cortex N-acetylaspartate/total creatine (NAA/tCr) loss in male recreational cannabis users. Biological Psychiatry June 1, 2007
- Neural substrates of faulty decision-making in abstinent marijuana users. Neuroimage June 2005
and 5 more in the library