| Title: | Short-term residual effects of smoked cannabis on simulated driving performance |
| Authors: | Kyle F. Mastropietro, Jake A. Rattigan, Anya Umlauf, David J. Grelotti, Marilyn A. Huestis, Raymond T. Suhandynata, Igor Grant, Robert L. Fitzgerald & Thomas D. Marcotte |
| Year: | 2025 |
| Journal: | Psychopharmacology |
A new study from Dr. Marcotte, Kyle Mastropietro (a trainee at the CMCR) and others from the CMCR investigated whether regular cannabis use has short-term “residual” effects on driving ability after a period of abstinence. While it is well established that cannabis can impair driving performance during acute intoxication, less is known about whether cognitive or motor effects linger for hours or days afterward.
In the largest such study to date, researchers from the CMCR recruited 191 regular cannabis users to complete a 25-minute simulated driving test after at least 48 hours of abstinence. Driving performance was measured using a Composite Drive Score that incorporated lane position, speed variability, car-following, and divided attention tasks. In a second analysis, 18 frequent heavy users were compared with 12 non-using controls.
The results were clear: cannabis use history, frequency, amount consumed, days since last use, and blood cannabinoid concentrations were not associated with poorer driving performance. Frequent users also performed no differently than non-users.
The findings suggest that residual cannabis effects—if present—may not translate into measurable impairments in a simulated driving environment after two days of abstinence. These new findings have implications for public health and for the enforcement of laws related to cannabis and driving. Future studies with larger control groups and more complex driving tasks will be important to confirm and extend these results.
Read the full publication here.
Citation: Mastropietro, K.F., Rattigan, J.A., Umlauf, A. et al. Short-term residual effects of smoked cannabis on simulated driving performance. Psychopharmacology (2025). https://doi.org/10.1007/s00213-025-06880-1