Correlation found between adult-use cannabis consumption and an increased rate of accidents, speed and running red lights
A new study from researchers at the prestigious American psychiatric institute, McLean Hospital, suggests heavy, frequent, adult-use cannabis consumption may affect a person’s driving ability, even after the user is no longer acutely intoxicated.
Published in the journal Drug and Alcohol Dependence, the authors of “Recreational Cannabis Use Impairs Driving Performance in the Absence of Acute Intoxication” found a correlation between adult-use cannabis consumption and an increased rate of accidents, speed and running red lights, compared to drivers who do not consume.
“Previous studies have demonstrated that cannabis use is associated with impaired driving performance, but thus far, research has primarily focused on the effects of acute intoxication,” wrote co-authors Staci Gruber, Mary Kathryn Dahlgren and their team.
During the study, the team recruited a small sample of 28 frequent, heavy, adult-use cannabis consumers (five women and 23 men), and 17 non-consumers (10 women and six men). The average age of the subjects was 23.
Participants qualified as cannabis users said they had consumed the drug five out of the previous seven days, and 1,500 times or more over the course of their lifetimes. The group abstained from cannabis consumption for 12 hours before participating in the study to ensure they were not acutely intoxicated.
Participants provided researchers with urine samples, which were screened for drugs including THC, as well as completed a psychological assessment and multiple questionnaires. The participants’ driving abilities were then tested in a simulator and evaluated by the team.
“Chronic, heavy, recreational cannabis use was associated with worse driving performance in non-intoxicated drivers, and earlier onset of use [consumption of the drug before the age of 16] was associated with greater impairment,” the study noted. “These results may be related to other factors associated with early exposure such as increased impulsivity,” it added.
Researchers noted a variety of limitations to the study, including the use of a driving simulator as opposed to real-life driving; being unsure of whether the users’ impulsivity occurred as a result of their cannabis use, or vice versa, and whether it was associated with early exposure; and the limited sample of participants.
“Given increased legalization of cannabis, growing numbers of cannabis consumers, and increased prevalence of drivers testing positive for cannabis metabolites, results from the current study underscore concerns about the impact of cannabis use on driving as a potential public safety issue,” the study concluded.
Written by Emma Spears