Study examines perceptions of the risk of driving while under the influence of cannabis

By Bhavana KunkalikarReviewed by Danielle Ellis, B.Sc.Apr 12 2023

In a recent study published in the Transportation Research Part F: Traffic Psychology and Behaviour journal, researchers explored how individuals perceive the risks associated with driving while under the influence of cannabis.

Perceiving driving under the influence of cannabis (DUIC) as dangerous or risky has been found to decrease the likelihood of engaging in the behavior. Cannabis usage and potency have increased in the US and Canada, while perceived harm has decreased. Studies have shown that despite a decrease in perceived risk associated with cannabis use, there is still an increased risk of collisions and impaired driving behavior and performance.

Study: Risk perceptions of driving under the influence of cannabis: Comparing medical and non-medical cannabis users. Image Credit: rbkomar / Shutterstock

About the study

In the present study, researchers compare the risk perceptions of DUIC between persons who use cannabis solely for non-medical purposes and those who use it for medical purposes or both.

The data used in this study were obtained from the Centre for Addiction and Mental Health (CAMH) Monitor 2017, a telephonic survey of adults in Canada that is regionally stratified and cross-sectional in design. The CAMH Monitor is performed quarterly using independent samples of around 750 completions each. The study focused on individuals who had used cannabis in the past year and provided responses about their perceptions of the risk of DUIC.

The 2017 survey enquired about DUIC risk perceptions in one of its two panels. The survey used a dual-frame sampling design that included landline as well as cellular telephone sampling frames. The sample was stratified by region, with an equal distribution of respondents from each province region. The data were weighted to account for regional representation and selection probabilities, while the age-by-gender distribution was restored through post-stratification adjustment using the latest census figures. The weighted sample is representative of non-institutionalized adults residing in Ontario.

The outcome measures were based on three DUIC risk perceptions: (1) DUIC raises the likelihood of being in a motor vehicle collision (MVC); (2) DUIC is less dangerous than DUI of alcohol (DUIA); and (3) The probability of getting caught by law enforcement for drinking and driving is higher than for DUIC. The survey used a 5-point scale for respondents to rate their agreement level with each statement.

Two survey items were used to measure the objective of using cannabis, which served as the focal exposure variable. The survey question inquired about the frequency of cannabis, hash, or marijuana usage within the last year. The second question was directed only to those who reported using cannabis in the past year and asked if they had used cannabis for medical purposes such as managing pain, glaucoma, nausea, multiple sclerosis symptoms, or other medical conditions. The sample was divided into two subgroups based on the responses received. One subgroup consisted of individuals who reported using non-medical cannabis exclusively, while the other subgroup consisted of individuals who reported using medical cannabis along with or without further non-medical cannabis usage.

Results

Approximately 62.3% of individuals reported using cannabis solely for non-medical reasons, while 37.7% reported using it for medical purposes or both medical and non-medical reasons. Almost 15% of the participants did not believe that DUIC increases the likelihood of being in an MVC. Over half of the participants agreed that DUIC is safer than DUIA, and nearly 75% agreed that the likelihood of being caught by law enforcement for DUIA was higher than for DUIC.

The study found a significant correlation between the type of cannabis user and their agreement on the safety of DUIC compared to DUIA. The other two findings did not show any significant association with the type of cannabis user. Cannabis users who used it for medical or dual purposes were found to be 45% more likely as compared to non-medical-only users, to believe that DUIC was safer than DUIA. The study also found that there was no significant association between the type of cannabis use and the other two outcomes.

Conclusion

The study findings showed that cannabis users who used it for medical or dual purposes did not differ from non-medical users in their perception of the risk of collision or being caught by police enforcement related to DUIC. However, medical or dual-purpose users were more likely to believe that DUIC was safer than DUIA compared to non-medical users.

The study suggests that education and awareness campaigns should focus on medical or dual-purpose cannabis users to emphasize that DUIC involves high-risk behavior, similar to DUIA, which has contributed to reductions in its incidence. Research on the correlation between DUIC and related risk perceptions for different types of cannabis users could aid road safety efforts. The impact of cultural or regional variations on risk perceptions and its effect on DUIC, along with its influence on public health messaging, should also be taken into account.