“Background: Cannabidiol (CBD) is being studied as a potential intervention for the people at clinical high risk for psychosis (CHR), though the mechanisms underlying its effects are not fully understood. Previous studies indicate that a single dose of CBD can normalize alterations in memory-related brain activation and modulate hippocampal glutamate levels in the early stages of psychosis. This study aimed to examine the acute effects of CBD on the relationship between hippocampal glutamate levels and brain activation during verbal memory in individuals at CHR.
Methods: A total of thirty-three participants (n = 33) at CHR were randomly assigned to receive a single 600 mg dose of CBD (CHR-CBD) or a placebo capsule (CHR-PLB). Age-matched healthy controls (HC) (n = 19) received no study drugs. Participants underwent MRI scanning while performing a verbal learning task, and proton magnetic resonance spectroscopy to measure hippocampal glutamate levels. Effect of group x hippocampal glutamate interactions on brain activation was tested.
Results: CHR-PLB showed positive correlation between hippocampal glutamate levels and dorsolateral prefrontal cortex (dlPFC) (Pcorr. = 0.0039) activation compared to HC during both verbal encoding and recall. Under a single dose of CBD, the glutamate-dlPFC activation relationship was negative and significantly different compared to placebo in CHR individuals (Pcorr. = 0.0001) during both verbal encoding and recall. The reversed correlation in CBD group was also observed in the parahippocampal gyrus (Pcorr. = 0.0022) and amygdala (Pcorr. = 0.0019) during verbal recall.
Conclusions: These findings suggest that CBD may normalise disrupted hippocampal-prefrontal glutamatergic coupling in CHR, highlighting its potential to target the neurochemical mechanisms underlying cognitive impairment.”
https://pubmed.ncbi.nlm.nih.gov/41337954
“To the best of our knowledge, this is the first study to demonstrate that a single dose of CBD may partially attenuate the altered relationship between hippocampal glutamate levels and activation in the prefrontal cortex, amygdala, and parahippocampal regions in individuals at CHR.”
“Single dose of CBD modulates hippocampal glutamate-prefrontal activation coupling in CHR.”
https://www.sciencedirect.com/science/article/abs/pii/S0925492725001507?via%3Dihub