Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment

Englund A, Morrison PD, Nottage J, Hague D, Kane F, Bonaccorso S, Stone JM, Reichenberg A, Brenneisen R, Holt D, Feilding A, Walker L, Murray RM, Kapur S.

Beckley Foundation, 2017.

https://beckleyfoundation.org/resource/cannabidiol-inhibits-thc-elicited-paranoid-symptoms-and-hippocampal-dependent-memory-impairment/

Abstract

Community-based studies suggest that cannabis products that are high in delta9-tetrahydrocannabinol (THC) but low in cannabidiol (CBD) are particularly hazardous for mental health.

Laboratory-based studies are ideal for clarifying this issue because THC and CBD can be administered in pure form, under controlled conditions. In a between-subjects design, we tested the hypothesis that pre-treatment with CBD inhibited THC-elicited psychosis and cognitive impairment.

Healthy participants were randomised to receive oral CBD 600 mg (n=22) or placebo (n=26), 210 min ahead of intravenous (IV) THC (1.5 mg). Post-THC, there were lower PANSS positive scores in the CBD group, but this did not reach statistical significance.

However, clinically significant positive psychotic symptoms (defined a priori as increases ? 3 points) were less likely in the CBD group compared with the placebo group, odds ratio (OR)=0.22 (?²=4.74, p<0.05).

In agreement, post-THC paranoia, as rated with the State Social Paranoia Scale (SSPS), was less in the CBD group compared with the placebo group (t=2.28, p<0.05).

Episodic memory, indexed by scores on the Hopkins Verbal Learning Task-revised (HVLT-R), was poorer, relative to baseline, in the placebo pre-treated group (-10.6 ± 18.9%) compared with the CBD group (-0.4% ± 9.7 %) (t=2.39, p<0.05).

These findings support the idea that high-THC/low-CBD cannabis products are associated with increased risks for mental health.