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Patients Exhibit Few Changes In Driving Performance Following Medical Cannabis Use


Every responsible cannabis consumer and advocate on earth recognizes that operating a motor vehicle on a public roadway while being intoxicated by any substance, including cannabis, is not safe.

With that being said, just because someone has cannabis in their system does not automatically mean that they are too impaired to safely operate a motor vehicle. Governments have seemed to struggle with that premise when crafting DUI laws in their jurisdictions.

Medical cannabis patients are particularly affected by bad cannabis DUI laws, as they essentially have to choose between taking their medicine or risking prosecution for simply having metabolized THC in their system.

Researchers in Australia recently conducted a study involving medical cannabis use and driving performance. Below is more information about it via a news release from NORML:

Hawthorne, Australia: Patients display few changes in their driving performance following the use of medical cannabis products, according to data published in the Journal of Psychopharmacology.

Australian researchers assessed simulated driving performance in a cohort of 40 patients authorized to consume cannabis. (Under Australian law, physicians may authorize cannabis products to patients unresponsive to conventional prescription treatments.) Participants completed a baseline driving assessment prior to their participation in the study. On the day of the study, patients consumed their typical dose of medical cannabis (either cannabis-based extracts or flowers) at the testing site prior to engaging in a battery of driving simulator tests.

Researchers identified no significant changes from patients’ baseline driving performance that would indicate psychomotor impairment.

They reported: “In this open-label semi-naturalistic study, simulated and perceived driving performance among 40 patients was assessed prior to and following self-administration of their own prescribed medical cannabis product. While oil users tended to have higher SDLP [standard deviation in lateral positioning] values, this was stable over time and there was no evidence of impairment for either administration route. Furthermore, the lack of changes in speed variability suggests a modest but sustained stabilization of vehicle control. … [N]o notable evidence of driving impairment (i.e. a significant decline in driving performance metrics within the simulated driving scenario) was observed for either consumption modality, relative to baseline.”

The study’s authors concluded, “Overall, this semi-naturalistic study suggests that medical cannabis, used as prescribed, has a negligible impact on simulated driving performance.”

The study’s findings are consistent with those of several others determining that daily cannabis consumers, and patients especially, exhibit tolerance to many of cannabis’ psychomotor-influencing effects. According to the findings of a literature review published in the journal of the German Medical Association, “Patients who take cannabinoids at a constant dosage over an extensive period of time often develop tolerance to the impairment of psychomotor performance, so that they can drive vehicles safely.”

Full text of the study, “A semi-naturalistic open-label study examining the effect of prescribed medical cannabis use on simulated driving performance,” appears in the Journal of PsychopharmacologyAdditional information is available in the NORML Fact Sheet, ‘Marijuana and Psychomotor Performance.’