Focus on older adults
In a comment, Anees Bahji, MD, an International Collaborative Addiction Medicine research fellow at the British Columbia Centre on Substance Use, called the study “interesting and relevant.”
He raised several questions regarding the “correlation between the level of a substance in a person’s system and the degree of impairment.” For example, “does the same level of THC in the blood affect us all the same way? And to what extent do the levels detected at the time of the analysis correlate with the level in the person’s system at the time of driving?”
An additional consideration “is for individuals with cannabis use disorder and for those who have developed tolerance to the psychoactive effects of THC: Does it affect their driving skills in the same way as someone who is cannabis naive?” asked Dr. Bahji, a clinical assistant professor at the University of Calgary (Alta.) who was not involved with the study.
Also commenting, Eric Sevigny, PhD, associate professor of criminal justice and criminology at Georgia State University, Atlanta, described it as a “well-designed study that adds yet another data point for considering appropriate road safety policy responses alongside ongoing cannabis liberalization.”
However, the findings “cannot say much about whether cannabis legalization leads to an increase in cannabis-impaired driving, because current research finds little correlation between biological THC concentrations and driving performance,” said Dr. Sevigny, who was not involved with the study.
The finding of “higher THC prevalence among older adults is also relevant for road safety, as this population has a number of concomitant risk factors, such as cognitive decline and prescription drug use,” Dr. Sevigny added.
The study was supported by the Canadian Institutes of Health Research. Dr. Brubacher and Dr. Sevigny disclosed no relevant financial relationships. Dr. Bahji reported receiving research funding from the Canadian Institutes of Health Research, the Calgary Health Trust, the American Psychiatric Association, NIDA, and the University of Calgary.
A version of this article first appeared on Medscape.com.