Résumé
As ~25% of Canadians used cannabis in 2024, it is imperative to understand the acute effects of intoxication on activities of daily living, including reaching movements. However, no study has examined how reaching is acutely impacted by ingestion of Δ9-tetrahydrocannabinol (THC, the psychoactive component in cannabis) or cannabidiol (CBD, commonly co-consumed with THC). Therefore, our purpose was to characterize the acute influence of THC and CBD ingestion on reaching performance. Ten (4 female) healthy, infrequent users (<1/week for 6 months) participated in four experimental sessions. Each session included a 60-trial reaching task before and ~3h after ingestion of capsules which contained: no THC or CBD (placebo), 10mg THC, 10mg CBD, or 10mg THC + 10mg CBD. Using a linear mixed effects model, post-pre change scores were compared for: movement time (MT), reaction time (RT), peak velocity (PV), time-to-peak velocity (ttPV), constant error (CE; final distance from the target), and variable error (VE; intraindividual CE variance). Compared to placebo, each drug intervention increased MT (THC: +19.06ms, CBD: +25.91ms, THC+CBD: +30.35ms), whereas only THC and THC+CBD increased RT (THC: +12.02ms, THC+CBD: +8.95ms). THC+CBD decreased PV (−60.0mm/s), and increased ttPV (+10.0ms), CE (+1.62mm), and VE (+0.33mm). CBD alone reduced CE (−1.84mm). These results demonstrate that ingesting THC in isolation or with CBD negatively impacts reaching speed and accuracy, while CBD alone led to slower but more accurate movements.
