Exploring perceptions on collision risk among people who drive after using cannabis

What you need to know:

This study described the detailed perspectives and personal stories of driving while under the influence of cannabis (DUIC) of 20 adults in a remedial program for impaired driving. Many participants felt that driving after using cannabis is less risky than after drinking alcohol or using other drugs. Participants’ feelings were mixed on the dangers of driving high. Some felt using cannabis does not increase the risk of collision and many felt they were less likely than others to get into a car crash after cannabis use. Some stated that using cannabis while driving was more accepted by their peers than family members, but this may have been because they trusted the opinions of other cannabis users more than non-users.


This Research Snapshot looks at the article, “Exploring perceptions among people who drive after cannabis use: Collision risk, comparative optimism and normative influence” by Wickens and colleagues, published in 2019 in the journal Drug and Alcohol Review. Read it below or download the PDF.

Research Snapshots are brief, clear language summaries of research articles, presented in a user-friendly format.

What is this research about?

view of driver's hands at the wheelCannabis is one of the psychoactive substances most commonly used prior to driving. With the legalization of cannabis, researchers are increasingly trying to understand people’s perceptions of DUIC to help inform public health and safety policies and programs.

Researchers have previously examined driver beliefs and perceptions of collision risk while DUIC. In this study, researchers expanded on this approach by asking drivers who were caught driving while impaired to share their perceptions of DUIC-related collision risk, and examined social influences and other factors that may have influenced their acceptance of this risk. 

What did the researchers do?

Researchers interviewed 20 adults from the Back on Track remedial program for convicted or suspended impaired drivers. They asked participants about their thoughts on the risk of having a collision after using cannabis, what driving skills may be affected by cannabis use, knowledge of others’ perceptions of cannabis use and collision risk, and whether the use of other drugs has any impact on collision risk.

What did the researchers find?

The researchers identified the following themes in participant responses:

  • Participants had mixed perceptions when discussing concerns about driving high. Some people felt that they would not be involved in a car crash after using cannabis but this would be more likely the case with novice or inexperienced drivers.
  • For persons who mentioned how cannabis could impact driving, skills related to attention such as distraction, ‘hyper-focusing’, reduced alertness, and feelings of paranoia and anxiety were the most frequently shared.
  • Participants generally felt that driving after using cannabis is less risky than when using other drugs, such as hallucinogens and stimulants.
  • Participants also mentioned that friends seem more accepting of DUIC than family members, and felt that the opinions of those who use cannabis are more credible than those who do not use cannabis.

Limitations and next steps

Since this study used an interview method, some participants may have felt they needed to respond to the questions in a way that was more acceptable to the interviewers. Participants may have had inaccurate recall of their past behaviour. Also, since participants were in a remedial program for impaired driving and were mostly male, their responses may be different from those of the general population and, in particular, female drivers.

How can you use this research?

The study provided insight into more personal stories and perceptions that contribute to DUIC, which can inform related laws, prevention programs, and services. The authors call for more research on the effects of cannabis while driving, particularly on perceptions of collision risk associated with cannabis compared to other drugs. They also recommend developing education and prevention programs to change people’s views of risk and peer norms.

About the researchers

Christine M. Wickens,1,2 Tara Marie Watson,1 Robert E. Mann,1,2 Bruna Brands1,3,4

1 Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, Canada

2 Dalla Lana School of Public Health, University of Toronto, Toronto, Canada

3 Controlled Substances Directorate, Health Canada, Ottawa, Canada

4 Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada


Cannabis, impaired driving, drug, risk perception, interview

This Research Snapshot was written by Neetu Shukla based on the article, “Exploring perceptions among people who drive after cannabis use: Collision risk, comparative optimism and normative influence” published in the Drug and Alcohol Review in 2019. DOI: 10.1111/dar.12923.

This Research Snapshot was developed by Evidence Exchange Network, part of the Provincial System Support Program at CAMH, with support from Health Canada. The views expressed herein do not necessarily represent the views of Health Canada.