Meta-Analysis Finds Cannabis Users Have Lower Levels of Key Brain Chemicals
A meta-analysis of brain spectroscopy studies found cannabis users had lower levels of GABA and N-acetylaspartate in the anterior cingulate cortex, and lower glutamate in the basal ganglia, suggesting altered neural functioning.
Quick Facts
What This Study Found
Compared to controls, cannabis users showed lower GABA and N-acetylaspartate (a marker of neural health) in the anterior cingulate cortex, lower glutamate in the basal ganglia/striatum, and lower glutamine and myo-inositol in the thalamus. All models had only 2-5 studies each.
Key Numbers
15 studies; 29 models; lower GABA and NAA in anterior cingulate; lower glutamate in basal ganglia; lower glutamine and myo-inositol in thalamus; all models had 2-5 studies.
How They Did This
Meta-analysis of 15 proton magnetic resonance spectroscopy (1H-MRS) studies using Hedges g with random-effects modeling. 29 models across gray matter brain regions. Pre-registered on PROSPERO.
Why This Research Matters
This is the first meta-analysis to consolidate brain chemistry studies in cannabis users. Altered GABA, glutamate, and NAA levels point to specific neurochemical pathways affected by cannabis, which could inform development of treatments for cannabis use disorder.
The Bigger Picture
Understanding which brain chemicals cannabis alters helps explain cognitive and behavioral effects. Lower GABA suggests reduced inhibitory neurotransmission. Lower NAA suggests potential impacts on neural integrity. These changes could underlie the cognitive effects seen in other studies.
What This Study Doesn't Tell Us
Very few studies per model (2-5), severely limiting statistical power and reliability. Could not test impacts of demographics, substance use patterns, or methodological factors. High heterogeneity across studies. Cross-sectional designs in underlying studies.
Questions This Raises
- ?Do these neurochemical changes reverse after cannabis cessation?
- ?Are the neurochemical changes dose-dependent?
Trust & Context
- Key Stat:
- Lower GABA, NAA, glutamate, and myo-inositol across brain regions
- Evidence Grade:
- Pre-registered meta-analysis, but very few studies per model (2-5) and high heterogeneity severely limit confidence.
- Study Age:
- 2025 publication
- Original Title:
- Neurometabolite Alterations Associated With Cannabis Use: A Proton Magnetic Resonance Spectroscopy Meta-Analysis.
- Published In:
- Human brain mapping, 46(8), e70236 (2025)
- Authors:
- Kirkland, Anna E(5), Browning, Brittney D(3), Green, ReJoyce, Agbeh, Samuel O, Squeglia, Lindsay M
- Database ID:
- RTHC-06837
Evidence Hierarchy
Frequently Asked Questions
Does cannabis change brain chemistry?
This meta-analysis found cannabis users had lower levels of several important brain chemicals: GABA (inhibitory neurotransmitter), N-acetylaspartate (neural health marker), glutamate, and myo-inositol (glial function marker). However, these findings are based on very few studies per brain region.
What brain regions does cannabis affect most?
The anterior cingulate cortex (involved in decision-making and emotion regulation) showed the most consistent changes, with lower GABA and NAA levels. The basal ganglia showed lower glutamate and the thalamus showed lower glutamine.
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Cite This Study
https://rethinkthc.com/research/RTHC-06837APA
Kirkland, Anna E; Browning, Brittney D; Green, ReJoyce; Agbeh, Samuel O; Squeglia, Lindsay M. (2025). Neurometabolite Alterations Associated With Cannabis Use: A Proton Magnetic Resonance Spectroscopy Meta-Analysis.. Human brain mapping, 46(8), e70236. https://doi.org/10.1002/hbm.70236
MLA
Kirkland, Anna E, et al. "Neurometabolite Alterations Associated With Cannabis Use: A Proton Magnetic Resonance Spectroscopy Meta-Analysis.." Human brain mapping, 2025. https://doi.org/10.1002/hbm.70236
RethinkTHC
RethinkTHC Research Database. "Neurometabolite Alterations Associated With Cannabis Use: A ..." RTHC-06837. Retrieved from https://rethinkthc.com/research/kirkland-2025-neurometabolite-alterations-associated-with
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.