Even after years of prior cannabis use, product use prior to driving can still cause impairment in older / substance experienced drivers, ages 65 – 79 years. These were among the findings of authors (DiCiano, P. et.al.) recently released in JAMA (January 2024) evaluating cannabis and its influence upon impaired driving among older adults. Researchers focused on lane weaving, speed control, and braking reaction time.
This study examined cannabis use and driving impairment in older drivers. This small-scale cohort study of this age group (N=31) occurred in Toronto, Canada from March to November 2022. Utilizing a driving simulator for evaluation, drivers consumed THC dominant cannabis, researchers examined driving behavior at 30 and 180 minutes (3-hours) after last cannabis exposure. While blood THC and THC metabolite levels were elevated at the 30-minute mark, it had declined at the 180-minute mark.
Weaving within a lane was the was the most common short-term driving behavior observed. Failure to maintain driving speed, as proposed by the authors, was in response to, “… the subject’s awareness that they were intoxicated”.Participants provided their personal subjective assessment of impairment and expressed being “less willing to drive” from 3 – 5 hours after their last exposure.
Of note was that the participants reported their cannabis habits as primarily recreational, more than once per week, and the cohort reported historical use for the past 40 years (mean value).
More research is needed to fully understand the effects of cannabis upon driving behavior. Based upon existing research, it demonstrates that cannabis does have a detrimental effect on users who elect to drive after consumption regardless of years of use and tolerance.
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Photo: Unsplash.com / McLean, E.