Does Cannabis Composition Matter? Differential Effects of Delta-9-tetrahydrocannabinol and Cannabidiol on Human Cognition

Cannabis's effect on cognition depends on its composition. Delta-9-tetrahydrocannabinol (Δ9-THC) acutely impairs memory and emotional processing, while limited evidence suggests cannabidiol (CBD) might improve cognition in cannabis users but not in those with neuropsychiatric disorders. Some acute cognitive impairments from Δ9-THC may be prevented if CBD is given before or alongside it. Δ9-THC and CBD show opposite effects on cognition-related brain activation. Overall, greater cognitive impairments occur with high-Δ9-THC or low-CBD cannabis, but it remains unclear whether specific CBD concentrations can outweigh Δ9-THC's harmful effects.

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Abstract

Purpose of ReviewThe lack of clarity about the effect of cannabis use on cognition may be attributable to the considerable heterogeneity among studies in terms of cannabis composition. This article selectively reviews studies examining the distinctive effects of cannabinoids on human cognition, particularly those of delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD).Recent FindingsResearch indicates that ∆9-THC administration acutely impairs cognition, particularly memory and emotional processing. Limited evidence suggests that CBD administration might improve cognition in cannabis users but not in individuals with neuropsychiatric disorders. Moreover, studies indicate that some acute Δ9-THC-induced cognitive impairments may be prevented if Δ9-THC is administered in combination or following CBD treatment. Δ9-THC and CBD have also shown opposite effects on cognition-related brain activation, possibly reflecting their antagonistic behavioral effects.SummaryResearch suggests greater cognitive impairments in individuals when exposed to high ∆9-THC or low CBD cannabis. It is unclear whether at specific concentrations CBD might outweigh any harmful effects of Δ9-THC on cognition.