Acute effects of partial CB1 receptor agonists on cognition - A meta-analysis of human studies.

Background: Impairment in cognition is frequently associated with acute cannabis consumption. However, some questions remain unanswered as to which deficits are most prominent and which demographic groups are most vulnerable.

Methods: A literature search yielded 40 experimental studies of acute administration of partial CB1 receptor agonists (i.e. cannabis, THC, and nabilone) that assessed cognitive dysfunction in 1403 healthy volunteers. Effect size estimates were calculated using the Comprehensive Meta-Analysis for the following six cognitive domains: attention, executive functions, impulsivity, speed of processing, verbal learning/memory, and working memory.

Results: There were small-to-moderate impairments across all cognitive domains. Deficits in verbal learning/memory and working memory were more prominent, whereas attention and impulsivity were the least affected. Meta-regression analysis revealed that the greater the male ratio is in a sample, the greater the negative effect of cannabinoids on speed of processing and impulsivity. Analysis of route of administration showed that the deficits in speed of processing were smaller in the oral, relative to smoking, vaping, and intravenous administration studies. A publication bias was observed.

Discussion: Verbal learning/memory and working memory are most prominently affected by acute administration of partial CB1 receptor agonists. The results are consistent with the residual cognitive effects that have been documented among chronic cannabis users.