CBD Affects the Autistic Brain Differently: MRI Study
What Researchers Found About Autism and Cannabis
The Study at a Glance
Published
Neuropsychopharmacology, 2019
Researchers
Multiple institutions (UK)
Study Type
Randomized Controlled TrialParticipants
34 patients · Single dose
Key Finding
CBD modulates glutamate-GABA systems, but prefrontal-GABA systems respond differently in ASD. Results do not speak to the efficacy of CBD for autism.
Key Finding: CBD modulates glutamate-GABA systems, but prefrontal-GABA systems respond differently in ASD. Results do not speak to the efficacy of CBD for autism.
What Researchers Studied About Autism and Cannabis
This study examined whether CBD changes brain chemistry differently in people with autism spectrum disorder (ASD) compared to neurotypical people.
Researchers measured glutamate (an excitatory brain chemical) and GABA (an inhibitory brain chemical) using magnetic resonance spectroscopy (MRS).
The focus was on brain regions linked to ASD: the basal ganglia and dorsomedial prefrontal cortex (DMPFC).
How This Randomized Controlled Trial Was Conducted
This was a randomized, double-blind, placebo-controlled, crossover trial.
34 healthy adult men participated: 17 with ASD and 17 neurotypical controls.
Participants received a single oral dose of 600 mg CBD or placebo. Brain scans were taken 2 hours post-dose (peak plasma levels). Test sessions were at least 13 days apart.
Autism Treatment Results
The Main Results:
- 1Across ALL groups: CBD increased subcortical Glx (glutamate) but DECREASED cortical Glx
- 2In CONTROLS: CBD increased GABA+ across brain regions
- 3In ASD: CBD DECREASED GABA+ across brain regions
- 4Group difference in GABA+ change in DMPFC was SIGNIFICANT
- 5CBD modulates glutamate-GABA systems in the brain
- 6BUT prefrontal-GABA systems respond DIFFERENTLY in ASD vs controls
- 7Results do NOT speak to clinical efficacy of CBD for autism
By the Numbers
| Statistic | What It Means |
|---|---|
| 34 men | 17 with ASD, 17 neurotypical controls |
| 600 mg CBD | Single oral dose administered |
| Opposite effect | CBD increased GABA in controls but decreased GABA in ASD |
| Significant | Group difference in DMPFC GABA+ change |
17 with ASD, 17 neurotypical controls
Single oral dose administered
CBD increased GABA in controls but decreased GABA in ASD
Group difference in DMPFC GABA+ change
What This Means for Autism Patients
This brain imaging study has an important finding: CBD affects the autistic brain differently than the neurotypical brain.
In people without autism, CBD increased GABA (a calming brain chemical). But in people with autism, CBD had the opposite effect, decreasing GABA.
This difference was significant in the prefrontal cortex, a brain region important for social behavior and executive function.
CRITICAL LIMITATION: This study only looked at brain chemistry changes from a single dose. It does NOT tell us whether CBD actually helps autism symptoms.
The researchers explicitly state: "Our results do not speak to the efficacy of CBD."
Future research is needed to determine: 1. Whether these acute brain changes translate to clinical improvement 2. What happens with chronic (long-term) CBD use 3. Whether CBD helps or potentially harms in ASD
Quick Answers: Autism and Cannabis
Direct answers based on the findings of this study:
Research Summary: Answers are based on published peer-reviewed studies and represent research findings, not medical recommendations. Individual results may vary. Always consult a healthcare provider before making treatment decisions.
How does CBD affect the autistic brain?
CBD affects autistic brains differently. A 2019 MRI study found CBD increased GABA (calming neurotransmitter) in controls but DECREASED GABA in people with ASD. This difference was significant in the prefrontal cortex.
Source: Pretzsch et al., Neuropsychopharmacology, 2019 (PMID: 30758329)
Does CBD treat autism?
Unknown from this study. While it found CBD affects autistic brains differently than neurotypical brains, the researchers stated "our results do not speak to the efficacy of CBD." Clinical efficacy was not assessed.
Source: Pretzsch et al., Neuropsychopharmacology, 2019 (PMID: 30758329)
Should I give CBD to my child with autism?
Caution is warranted. CBD had opposite effects on GABA in autistic vs neurotypical brains. Whether this is beneficial or harmful is unknown. Consult a physician before using CBD for autism.
Source: Pretzsch et al., Neuropsychopharmacology, 2019 (PMID: 30758329)
This is educational content, not medical advice
The research summarized here is for informational purposes only. Individual results may vary, and what works in studies may not work the same way for everyone. Always consult with a qualified healthcare provider before making changes to your treatment plan or starting medical cannabis therapy.
Important Limitations
This study has some caveats to keep in mind when interpreting the results:
- Single dose only (no chronic treatment)
- Does NOT assess clinical efficacy
- Small sample (34 participants)
- Men only
- Healthy adults only (no severe ASD)
- Brain chemistry change does not equal symptom improvement
The Bottom Line on Cannabis for Autism
This MRI study of 34 men found CBD has opposite effects on GABA in autistic vs neurotypical brains. In controls, CBD increased the calming neurotransmitter GABA. In ASD, CBD decreased GABA. This suggests CBD affects the autistic brain differently, but the study explicitly does NOT assess whether CBD helps autism symptoms.
Do You Qualify for Medical Marijuana?
If you're living with Autism, you may qualify for a medical marijuana card. Our licensed physicians can evaluate you from home via telehealth.
Related Research & Resources
Related Research
Condition Research
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Source
Pretzsch CM, Freyberg J, Voinescu B, et al. "Effects of cannabidiol on brain excitation and inhibition systems; a randomised placebo-controlled single dose trial during magnetic resonance spectroscopy in adults with and without autism spectrum disorder" Neuropsychopharmacology. 2019. DOI: 10.1038/s41386-019-0333-8
Important Information
Study Age: This study was published 7 years ago. Newer research may have updated or refined these findings.
Not Medical Advice: This research summary is for educational purposes only. It should not be used to diagnose, treat, cure, or prevent any disease or medical condition. Always consult a qualified healthcare provider before starting or changing any treatment.
Individual Variation: Research findings represent group averages. Your individual response to cannabis may differ based on genetics, other medications, underlying conditions, and many other factors.
Last reviewed: January 25, 2026
Important Notices
Research Summary Disclaimer
This content represents our interpretation of published scientific research for educational purposes. It should not be used to make treatment decisions without consulting a qualified healthcare provider. Individual results may vary from study findings.
FDA Notice
These statements have not been evaluated by the FDA. Cannabis is not intended to diagnose, treat, cure, or prevent any disease. The FDA has not approved cannabis for any medical condition except specific prescription medications.
Copyright & Fair Use
Research summaries are provided under fair use (17 U.S.C. § 107) for educational purposes. We provide brief summaries with attribution, not full reproductions. All studies remain the intellectual property of their respective authors and publishers.
Data Sources
Study information sourced from PubMed®, U.S. National Library of Medicine. Inclusion does not imply endorsement by NLM, NIH, or the federal government.
For complete information, see our Terms of Use and Research Content Policy.
FAQs: Cannabis for Autism
Does CBD work differently in autistic brains?
Yes. This MRI study found CBD had opposite effects on GABA (a calming neurotransmitter) in autistic vs neurotypical brains. CBD increased GABA in controls but decreased it in ASD.
Does CBD help autism symptoms?
Unknown from this study. The researchers explicitly stated their "results do not speak to the efficacy of CBD." Only brain chemistry was measured, not symptoms.
Is CBD safe for people with autism?
Unknown, more research needed. This single-dose study cannot determine safety. The finding that CBD affects autistic brains differently raises questions about whether effects are beneficial or potentially harmful.