Neurocognitive performance during acute THC intoxication in heavy and occasional cannabis users.
J G Ramaekers, G Kauert, E L Theunissen, S W Toennes, M R Moeller
Journal of psychopharmacology (Oxford, England) May 2009 DOI: 10.1177/0269881108092393 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized controlled trial Placebo-controlled Double-blind Peer reviewed |
|---|---|
| Sample size | 24 |
| Population | Occasional and heavy cannabis users |
| Intervention | THC |
| Dose | 500 microg/kg |
| Duration | 0 to 8 hours after smoking |
| Measures | critical tracking task, divided attention task, stop signal task, Tower of London |
| Topics | Cannabis |
| Key findings | THC significantly impaired performance in occasional users on critical tracking, divided attention, and stop signal tasks, but in heavy users only stop reaction time increased, particularly at high THC concentrations. No persistent performance differences were observed between groups due to residual THC, indicating cannabis use history strongly determines behavioral response. |
Abstract
Performance impairment during Delta(9)-tetrahydrocannabinol (THC) intoxication has been well described in occasional cannabis users. It is less clear whether tolerance develops to the impairing effects of THC in heavy users of cannabis. The aim of the present study was to assess neurocognitive performance during acute THC intoxication in occasional and heavy users. Twenty-four subjects (12 occasional cannabis users and 12 heavy cannabis users) participated in a double-blind, placebo-controlled, two-way mixed model design. Both groups received single doses of THC placebo and 500 microg/kg THC by smoking. Performance tests were conducted at regular intervals between 0 and 8 h after smoking, and included measures of perceptual motor control (critical tracking task), dual task processing (divided attention task), motor inhibition (stop signal task) and cognition (Tower of London). THC significantly impaired performance of occasional cannabis users on critical tracking, divided attention and the stop signal task. THC did not affect the performance of heavy cannabis users except in the stop signal task, i.e. stop reaction time increased, particularly at high THC concentrations. Group comparisons of overall performance in occasional and heavy users did not reveal any persistent performance differences due to residual THC in heavy users. These data indicate that cannabis use history strongly determines the behavioural response to single doses of THC.