title: Cannabis and its effects on driving skills.
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.
authors.affiliation: Traffic Medicine and Psychology Unit, University Center of Legal Medicine, University Hospital of Geneva, Rue Gabrielle-Perret-Gentil 4, 1205 Genève, Switzerland. Electronic address: percy.bondallaz@hcuge.ch.
authors.forename: Percy
authors.initials: P
authors.lastname: Bondallaz
authors.affiliation: Traffic Medicine and Psychology Unit, University Center of Legal Medicine, University Hospital of Geneva, Rue Gabrielle-Perret-Gentil 4, 1205 Genève, Switzerland; Department of Ambulatory Care and Community Medicine, University of Lausanne, Rue du Bugnon 44, 1011 Lausanne, Switzerland; Traffic Medicine and Psychology Unit, University Center of Legal Medicine, University Hospital of Lausanne, Lausanne, Switzerland. Electronic address: bernard.favrat@chuv.ch.
authors.forename: Bernard
authors.initials: B
authors.lastname: Favrat
authors.affiliation: Department of Clinical Pharmacology and Toxicology, Centre Hospitalier Universitaire Vaudois, Rue du Bugnon 17, 1011 Lausanne, Switzerland. Electronic address: haithem.chtioui@chuv.ch.
authors.forename: Haïthem
authors.initials: H
authors.lastname: Chtioui
authors.affiliation: CIBM (Centre d'Imagerie Biomédicale), Centre Hospitalier Universitaire Vaudois (CHUV), Rue du Bugnon 46, 1011 Lausanne, Switzerland; Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne, Rue du Bugnon 46, 1011 Lausanne, Switzerland. Electronic address: eleonora.fornari@chuv.ch.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Fornari
authors.affiliation: Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV) and University of Lausanne, Rue du Bugnon 46, 1011 Lausanne, Switzerland. Electronic address: philippe.maeder@chuv.ch.
authors.forename: Philippe
authors.initials: P
authors.lastname: Maeder
authors.affiliation: Forensic Toxicology and Chemistry Unit, University Center of Legal Medicine, University Hospital of Lausanne, Chemin de la Vulliette 4, 1000 Lausanne 25, Switzerland. Electronic address: christian.giroud@chuv.ch.
authors.forename: Christian
authors.initials: C
authors.lastname: Giroud
mesh_terms: D000428:Alcohol Drinking / Q000009:adverse effects; D003071:Cognition / Q000187:drug effects; D000066448:Driving Under the Influence / Q000331:legislation & jurisprudence; D013759:Dronabinol / Q000032:analysis; D004347:Drug Interactions; D006801:Humans; D002189:Marijuana Abuse / Q000150:complications*; D000074609:Marijuana Use / Q000009:adverse effects*; D064086:Medical Marijuana / Q000009:adverse effects; D011597:Psychomotor Performance / Q000187:drug effects; D011640:Public Policy; D015813:Substance Abuse Detection
chemical_list: D064086:Medical Marijuana; D013759:Dronabinol
keywords: Cannabis; Driving; Fitness to drive; Psychomotor effects; THC