Findings
Δ9-THC, impairment of cognitive and psychomotor ability
In this randomized clinical trial including 18 adult participants, ingestion of 20 mg Δ9-THC + 640 mg CBD resulted in stronger subjective drug effects, greater impairment of cognitive and psychomotor ability, and greater increase in heart rate relative to 20 mg Δ9-THC alone and placebo. These effects appear to be mediated by CBD inhibition of Δ9-THC and 11-OH-Δ9-THC metabolism.