Medical Marijuana and Driving: a Review

Abstract

Medical marijuana remains a highly debated treatment regimen despite removal of state penalties against care providers prescribing the drug and patients treated with the drug in many areas of the USA. The utility of marijuana in specific medical conditions has been studied at length, but its effects on driving performance and risk of motor vehicle collision remain unclear. As with other medications that affect psychomotor function, the healthcare provider should be informed of the potential risks of driver safety prior to prescribing this psychotropic drug to give appropriate anticipatory guidance for appropriate use. The goal of this narrative review is to assess the current literature regarding marijuana as it relates to driving performance and traffic safety. With a foundation in the pharmacology of cannabinoids, we consider the limitations of testing cannabinoid and metabolite concentration. In addition, we will review studies on driving performance and epidemiological studies implicating marijuana in motor vehicle collisions. The increasing prevalence of medical marijuana laws in the USA suggests that clinicians should be aware of marijuana's influence on public safety. Patients should abstain from driving for 8 h if they achieve a subjective "high" from self-treatment with smoked marijuana and should be aware of the cumulative effects of alcohol and other psychoactive xenobiotics.

The Impact of Marijuana Policies on Youth: Clinical, Research, and Legal Update

“…79,80 Physical effects on coordination and reaction time raise serious concerns about the contribution of marijuana intoxication to motor vehicle injuries and deaths. 81,82 Medical consequences include respiratory effects 83 and the long-term effects of exposure to carcinogenic components of marijuana smoke, with a recent study from New Zealand finding elevated rates of lung cancer in adults with histories of long-term marijuana smoking. 84 Studies have also shown connections between chronic marijuana use and mental health disorders such as anxiety and schizophrenia.…”

Frequent marijuana use and driving risk behaviours in Canadian youth

“…driving a car, riding a motorbike, using machinery, boating, and so on)? Age includes abstainers (n=55 and n=81 for males and females) who indicated that they had used marijuana prior to the last 12 months limited (28). Educational approaches to harm reduction have shown some success in relation to reducing cigarette smoking and alcohol-related harms (5) and may be useful for addressing marijuana-related harms.…”

“…Educational approaches could include adding labels warning against operating a vehicle or machinery while using marijuana to dose packaging and advocating for guidelines established in research on the effects of medical marijuana. The latter propose avoiding driving or operating machinery while experiencing subjective highs and for the following 8 hours (28). Some research suggests that individuals who experience subjective highs enact compensatory behaviours that can reduce risks (e.g., slowing down or increasing following distances).…”

Adverse Effects of Marijuana Use

“…A review by Neavyn et al (2014) showed agreement among multiple studies that recreational marijuana use negatively impacts psychomotor functioning including coordination, motor performance, and reaction time, which are all crucial tasks when driving a vehicle. The additive effect of marijuana use, impaired cognition, and reduced psychomotor skill can result in a dangerous situation for individuals behind the wheel as well as the other drivers on the roadway.…”