Cannabis Actually Normalized Brain Network Connectivity in Schizophrenia Patients
In a pilot fMRI study, schizophrenia patients showed abnormal default mode network hyperconnectivity at baseline, but cannabinoid administration reduced this hyperconnectivity and improved the brain network patterns associated with working memory.
Quick Facts
What This Study Found
At baseline, schizophrenia patients showed DMN hyperconnectivity (correlated with positive symptom severity) and reduced anticorrelation between the DMN and executive control network compared to controls. After cannabinoid administration, DMN hyperconnectivity was reduced and DMN-ECN anticorrelation increased. The magnitude of anticorrelation after cannabinoid administration correlated with working memory performance.
Key Numbers
12 patients, 12 controls. DMN hyperconnectivity at baseline correlated with positive symptom severity. After cannabinoid administration, DMN connectivity normalized toward control levels. Post-cannabinoid DMN-ECN anticorrelation correlated with working memory performance.
How They Did This
Pilot study with 12 schizophrenia-CUD patients and 12 healthy controls. Resting-state fMRI at baseline and after patients smoked a 3.6% THC cannabis cigarette or ingested a 15 mg THC pill. Default mode network connectivity analyzed.
Why This Research Matters
DMN hyperconnectivity is a consistent finding in schizophrenia and is linked to psychotic symptoms. The remarkable finding that cannabinoids normalized this aberrant connectivity suggests a potential mechanism by which some schizophrenia patients may derive benefit from cannabis use, despite its general risks.
The Bigger Picture
This pilot challenges the simple narrative that cannabis is uniformly harmful in psychosis. The finding that cannabinoids normalized a key brain network abnormality suggests the relationship between cannabis and psychosis is more complex than currently understood.
What This Study Doesn't Tell Us
Very small pilot (n=12 per group). No placebo control for the cannabinoid administration. Low THC dose (3.6% or 15 mg). Cannot determine whether this network normalization translates to clinical benefit. Acute effects may differ from chronic effects.
Questions This Raises
- ?Could cannabinoids be therapeutically useful for normalizing DMN connectivity in schizophrenia?
- ?Is this effect specific to THC, or would CBD produce similar network changes?
- ?Does this explain why some schizophrenia patients report benefits from cannabis?
Trust & Context
- Key Stat:
- Cannabinoid administration reduced default mode network hyperconnectivity in schizophrenia patients and improved the brain pattern associated with working memory.
- Evidence Grade:
- Preliminary - very small pilot without placebo control, but novel and clinically provocative finding.
- Study Age:
- Published in 2018.
- Original Title:
- Understanding marijuana's effects on functional connectivity of the default mode network in patients with schizophrenia and co-occurring cannabis use disorder: A pilot investigation.
- Published In:
- Schizophrenia research, 194, 70-77 (2018)
- Authors:
- Whitfield-Gabrieli, Susan, Fischer, Adina S, Henricks, Angela M(2), Khokhar, Jibran Y, Roth, Robert M, Brunette, Mary F, Green, Alan I
- Database ID:
- RTHC-01875
Evidence Hierarchy
A small preliminary study to test whether a larger study is feasible.
What do these levels mean? →Frequently Asked Questions
Can cannabis improve brain function in schizophrenia?
This small pilot study found that cannabinoid administration normalized an abnormal brain network pattern (DMN hyperconnectivity) in schizophrenia patients, and this normalization correlated with better working memory. However, this is a very preliminary finding that needs replication.
What is the default mode network?
The DMN is a brain network active during rest and internal thought. In schizophrenia, this network is often hyperconnected (overactive), which correlates with psychotic symptoms. This study found cannabinoids reduced this hyperconnectivity toward normal levels.
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Cite This Study
https://rethinkthc.com/research/RTHC-01875APA
Whitfield-Gabrieli, Susan; Fischer, Adina S; Henricks, Angela M; Khokhar, Jibran Y; Roth, Robert M; Brunette, Mary F; Green, Alan I. (2018). Understanding marijuana's effects on functional connectivity of the default mode network in patients with schizophrenia and co-occurring cannabis use disorder: A pilot investigation.. Schizophrenia research, 194, 70-77. https://doi.org/10.1016/j.schres.2017.07.029
MLA
Whitfield-Gabrieli, Susan, et al. "Understanding marijuana's effects on functional connectivity of the default mode network in patients with schizophrenia and co-occurring cannabis use disorder: A pilot investigation.." Schizophrenia research, 2018. https://doi.org/10.1016/j.schres.2017.07.029
RethinkTHC
RethinkTHC Research Database. "Understanding marijuana's effects on functional connectivity..." RTHC-01875. Retrieved from https://rethinkthc.com/research/whitfield-gabrieli-2018-understanding-marijuanas-effects-on
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.