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.
Neuroscience researchers, addiction specialists, cannabis pharmacology researchers
Lower GABA, NAA, glutamate, and myo-inositol across brain regions
What the researchers 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.
Why it 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 numbers in context
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 the study worked
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.
What this study cannot 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.
How to read the evidence
Pre-registered meta-analysis, but very few studies per model (2-5) and high heterogeneity severely limit confidence.
When this study was published
2025 publication
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.
Questions still open
- Do these neurochemical changes reverse after cannabis cessation?
- Are the neurochemical changes dose-dependent?
Common questions
Does cannabis change brain chemistry?
What brain regions does cannabis affect most?
Read the original research
Neurometabolite Alterations Associated With Cannabis Use: A Proton Magnetic Resonance Spectroscopy Meta-Analysis.
Human brain mapping, 46(8), e70236
Citation
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
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