Edible THC impairment peaks hours after the dose

The psychoactive component of cannabis, Δ9-tetrahydrocannabinol (THC), is known to alter cognitive-motor function; however, despite the high prevalence of cannabis use globally, the time course of the effects of ingesting THC is unclear. To allow future studies to accurately time the assessment of the impacts of cannabis on behaviour, this study aimed to establish a detailed time series of subjective intoxication and cognitive-motor performance following THC ingestion. Fifteen infrequent cannabis users (8 females; 29.4 ± 8.1 y) completed a testing battery before (baseline) and at 11 timepoints (0-6 h) after ingesting 10 mg of THC. A subset of seven participants (3 females; 32.0 ± 8.8 y) also performed an identical control session, with no drug administered. Subjective drug effects and cardiovascular responses were recorded, and cognitive-motor function was measured via performance on simple reaction time, go/no-go reaction time, and Corsi block tapping tasks. Linear mixed-effects models were used to determine if subjective and objective measures changed during the time series. Compared to baseline, participants reported significant subjective drug effects 1-6 h post-ingestion. Heart rate was elevated from 3-6 h, whereas blood pressure was elevated at timepoints between 1-4 h. Individuals demonstrated a robust increase of simple reaction time from 1-6 h, reduced go/no-go accuracy between 1.5-6 h, and impaired Corsi blocking tapping performance between 1-5 h. Overall, the ideal window to test the cognitive-motor effects of cannabis intoxication appears at 3-4 h post-THC ingestion, with a marked perception of feeling high between 2-5 h.