Cannabinoid and Glutamate Systems May Jointly Disrupt Brain Oscillations in Psychosis | Research

The takeaway

CB1 receptor agonists and NMDA receptor antagonists both reduce GABAergic signaling on interneurons, disrupting the theta and gamma brain oscillations that are critical for cognition - a potential shared mechanism underlying psychosis.

Schizophrenia researchers, neuroscientists, psychopharmacologists.

CB1R agonists and NMDAR antagonists both reduce GABA interneuron signaling, converging on the same disrupted brain oscillation patterns seen in schizophrenia.

What the researchers found

CB1Rs and NMDARs have direct and indirect interactions in brain regions implicated in schizophrenia (hippocampus, frontal cortex, cerebellum). Both systems converge on GABA interneurons: CB1R agonists and NMDAR antagonists each reduce GABAergic neurotransmission, leading to unsynchronized pyramidal neuron activity and disrupted neural oscillations involved in information processing.

Why it matters

Schizophrenia research has developed separate cannabinoid and glutamate models of the disorder. This review argues these are not competing explanations but complementary mechanisms that converge on disrupted brain oscillations, potentially explaining why cannabis use increases psychosis risk.

The numbers in context

Theta oscillations (4-7 Hz) and gamma oscillations (30-80 Hz) are the key frequencies discussed. Three brain regions examined: hippocampus, frontal cortex, and cerebellum.

How the study worked

Review synthesizing literature on cannabinoid-glutamate interactions in the context of neural oscillations and schizophrenia, aiming to bridge the "cannabis model" and "ketamine model" of psychosis.

What this study cannot tell us

Largely theoretical synthesis. Much evidence comes from acute drug administration studies rather than chronic exposure. The relationship between oscillatory disruptions and clinical symptoms is complex and not fully understood.

How to read the evidence

Moderate - well-reasoned theoretical synthesis of existing evidence, but largely speculative regarding combined mechanisms.

When this study was published

Published in 2018.

The bigger picture

Unifying the cannabinoid and glutamate models of schizophrenia could lead to more comprehensive treatment approaches that target the shared downstream effects rather than individual receptor systems.

Questions still open

Could combined CB1R and NMDAR modulation be more effective than targeting either system alone? Do chronic cannabis users show the predicted oscillatory disruptions? Could oscillatory measures serve as biomarkers for cannabis-related psychosis risk?

Common questions

How do cannabis and glutamate systems relate in the brain?

CB1 cannabinoid receptors and NMDA glutamate receptors interact directly and indirectly in key brain regions. Both systems affect GABA interneurons, and disrupting either one can produce similar effects on brain oscillations linked to psychosis.

What are brain oscillations and why do they matter for psychosis?

Brain oscillations are rhythmic patterns of neural activity (like theta at 4-7 Hz and gamma at 30-80 Hz) that coordinate information processing. Disrupted oscillations are consistently found in schizophrenia and may underlie cognitive symptoms.

Read the original research

Cannabinoid-glutamate interactions and neural oscillations: implications for psychosis.

The European journal of neuroscience, 48(8), 2890-2902

View on PubMed ↗Publisher’s paper ↗

Citation

Sherif, Mohamed A; Cortes-Briones, Jose A; Ranganathan, Mohini; Skosnik, Patrick D. (2018). Cannabinoid-glutamate interactions and neural oscillations: implications for psychosis.. The European journal of neuroscience, 48(8), 2890-2902. https://doi.org/10.1111/ejn.13800