Cannabis and its effects on driving skills.
Percy Bondallaz, Bernard Favrat, Haïthem Chtioui, Eleonora Fornari, Philippe Maeder, Christian Giroud
Forensic Science International November 2016 DOI: 10.1016/j.forsciint.2016.09.007 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Topics | Cannabis |
| Keywords | Driving Fitness to drive Psychomotor effects |
| Key findings | The review reports that cannabis impairs driving performance, increasing lane weaving and mean distance headway to the preceding vehicle, and causes acute and long-term dose-dependent impairments in cognitive and psychomotor functions that extend beyond a few weeks after cessation. Combining alcohol and cannabis produces greater odds of driving errors than either alone, and blood sampling is described as the most effective way to evaluate driver impairment. |
Abstract
Traffic policies show growing concerns about driving under the influence of cannabis, since cannabinoids are one of the most frequently encountered psychoactive substances in the blood of drivers who are drug-impaired and/or involved in accidents, and in the context of a legalization of medical marijuana and of recreational use. The neurobiological mechanisms underlying the effects of cannabis on safe driving remain poorly understood. In order to better understand its acute and long-term effects on psychomotor functions involved in the short term ability and long-term fitness to drive, experimental research has been conducted based on laboratory, simulator or on-road studies, as well as on structural and functional brain imaging. Results presented in this review show a cannabis-induced impairment of actual driving performance by increasing lane weaving and mean distance headway to the preceding vehicle. Acute and long-term dose-dependent impairments of specific cognitive functions and psychomotor abilities were also noted, extending beyond a few weeks after the cessation of use. Some discrepancies found between these studies could be explained by factors such as history of cannabis use, routes of administration, dose ranges, or study designs (e.g. treatment blinding). Moreover, use of both alcohol and cannabis has been shown to lead to greater odds of making an error than use of either alcohol or cannabis alone. Although the correlation between blood or oral fluid concentrations and psychoactive effects of THC needs a better understanding, blood sampling has been shown to be the most effective way to evaluate the level of impairment of drivers under the influence of cannabis. The blood tests have also shown to be useful to highlight a chronic use of cannabis that suggests an addiction and therefore a long-term unfitness to drive. Besides blood, hair and repeated urine analyses are useful to confirm abstinence.
Comparable studies
Other narrative reviews on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Causal association between cannabis and psychosis: examination of the evidence | 2004 | Review | |
| Cannabis sativa: A comprehensive ethnopharmacological review of a medicinal plant with a long history. General (historical and pharmacological review) | 2018 | Review | |
| Psychiatric effects of cannabis | 2001 | Review | |
| Beyond THC: The New Generation of Cannabinoid Designer Drugs | 2011 | Review | |
| Cannabidiol, a Cannabis sativa constituent, as an antipsychotic drug | 2006 | Review |
Citations in the library
Cited by 6
- Preliminary pharmacokinetic and psychophysical investigations after controlled oral and inhalative consumption of hexahydrocannabinol (HHC) Scientific Reports March 24, 2025
- Self-Regulation of Driving Behavior Under the Influence of Cannabis: The Role of Driving Complexity and Driver Vision. Human factors November 2023
- Recommendations for Reducing the Risk of Cannabis Use-Related Adverse Psychosis Outcomes: A Public Mental Health-Oriented Evidence Review Journal of dual diagnosis July 3, 2023
- The why behind the high: determinants of neurocognition during acute cannabis exposure. Nature Reviews Neuroscience July 1, 2021
- Developing a phone-based measure of impairment after acute oral ∆9-tetrahydrocannabinol. Journal of Psychopharmacology September 1, 2019
and 1 more in the library
Cites 19
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- Neurophysiological functioning of occasional and heavy cannabis users during THC intoxication Psychopharmacology October 5, 2011
- Cannabis effects on driving longitudinal control with and without alcohol. Journal of Applied Toxicology November 2016
- Weed or Wheel! fMRI, Behavioural, and Toxicological Investigations of How Cannabis Smoking Affects Skills Necessary for Driving PLoS One January 2, 2013
and 14 more in the library