Smoked Cannabis' Psychomotor and Neurocognitive Effects in Occasional and Frequent Smokers
Nathalie A. Desrosiers, Johannes G. Ramaekers, Émeline Chauchard, David A. Gorelick, Marilyn A. Huestis
Journal of Analytical Toxicology March 4, 2015 DOI: 10.1093/jat/bkv012 via OpenAlex
Summary
THC, the main psychoactive compound in cannabis, impairs psychomotor performance, cognition, and driving ability. Occasional cannabis smokers showed significantly more difficulty compensating for tracking error and greater decline in divided attention performance than frequent smokers after smoking one 6.8% THC cigarette. No differences between groups were found on working memory or risk-taking tasks. The results suggest that frequent users develop some tolerance to psychomotor impairment, with implications for driving under the influence cases.
Study at a glance
| Characteristics | Controlled within-subjects study Peer reviewed |
|---|---|
| Sample size | 25 |
| Population | Occasional (<2x/week) and frequent (≥4x/week) cannabis smokers |
| Intervention | smoking one 6.8% THC cigarette |
| Dose | one 6.8% THC cigarette |
| Duration | 22.5 hours after starting smoking |
| Topics | Cannabis |
| Keywords | Psychomotor learning Neurocognitive Cognition Psychology |
| Citations | 136 |
| Key finding | Occasional smokers showed greater psychomotor impairment after smoking cannabis than frequent smokers, indicating tolerance in frequent users. |
Abstract
Δ9-Tetrahydrocannabinol (THC), the primary psychoactive constituent in cannabis, impairs psychomotor performance, cognition and driving ability; thus, driving under the influence of cannabis is a public safety concern. We documented cannabis' psychomotor, neurocognitive, subjective and physiological effects in occasional and frequent smokers to investigate potential differences between these smokers. Fourteen frequent (≥4x/week) and 11 occasional (<2x/week) cannabis smokers entered a secure research unit ∼19 h prior to smoking one 6.8% THC cigarette. Cognitive and psychomotor performance was evaluated with the critical tracking (CTT), divided attention (DAT), n-back (working memory) and Balloon Analog Risk (BART) (risk-taking) tasks at -1.75, 1.5, 3.5, 5.5 and 22.5 h after starting smoking. GLM (General Linear Model) repeated measures ANOVA was utilized to compare scores. Occasional smokers had significantly more difficulty compensating for CTT tracking error compared with frequent smokers 1.5 h after smoking. Divided attention performance declined significantly especially in occasional smokers, with session × group effects for tracking error, hits, false alarms and reaction time. Cannabis smoking did not elicit session × group effects on the n-back or BART. Controlled cannabis smoking impaired psychomotor function, more so in occasional smokers, suggesting some tolerance to psychomotor impairment in frequent users. These data have implications for cannabis-associated impairment in driving under the influence of cannabis cases.