Skip to main content

Main menu

  • About Us
    • Leadership
    • Our Team
    • Vision, Mission and Values
    • Health and Economic Impact
    • Research Impact Video
    • Strategic Plan
  • Our Research
    • Research Focus
      • Brain Health
      • Cancer
      • Digital Health and Artificial Intelligence
      • Heart Health
      • Healthy Aging and Mobility
      • Immune System
      • Injury and Rehabilitation
      • Lung Health
      • Mental Health and Substance Use
    • Research Centres and Programs
      • BC Centre on Substance Use
      • Centre for Aging SMART
      • Centre for Cardiovascular Innovation
      • Centre for Clinical Epidemiology and Evaluation
      • Centre for Lung Health
      • Djavad Mowafaghian Centre for Brain Health
      • Immunity and Infection Research Centre
      • International Collaboration On Repair Discoveries
      • M. H. Mohseni Institute of Urologic Sciences
      • Ovarian Cancer Research Centre
      • Community Research Program
      • Emergency Medicine Research Program
      • Hematology Research Program
      • Skin Research Program
      • Other Research Focus Areas
    • News and Stories
    • Researcher Directory
    • Events and Workshops
  • Research Services
    • New to VCHRI
      • Working at VCHRI
      • Regulations and Training
      • Membership with VCHRI
      • Learning and Development
    • Starting Your Project
      • Research Facilitation
      • Awards and Funding
      • Grant Management
      • Operational Approval
      • CST Cerner
    • Developing Your Project
      • Clinical Trials Administration
      • Clinical Research Unit
      • Research Privacy
      • Financial Policies and Procedures
    • Additional Support
      • Indigenous Health Research Unit
      • VCH-VCHRI AI Hub
      • Communications and Media Relations
      • Study Recruitment Support
      • Innovation and Industry Partnership
    • Internal Awards
    • Clinical Research
    • Indigenous Research
  • Participate in Research
    • Reasons to Participate
    • Participant Stories
    • Find a Study
    • Recruitment Support

User menu

  • Log in

Breadcrumb

  1. Home
  2. Our Research
  3. News and Stories
  4. Cannabis legalization may have upped the number of older adults driving high

Cannabis legalization may have upped the number of older adults driving high

Stories Jun 23, 2022 3 minutes

Older and male drivers were over-represented among those admitted to hospital in B.C.

Following the legalization of cannabis in Canada, drivers presenting to some British Columbia hospitals with moderate injuries were twice as likely to have over-the-limit tetrahydrocannabinol (THC) levels in their bloodstreams. This revelation was one of several presented in a recent study led by Vancouver Coastal Health Research Institute (VCHRI) clinician-scientist Dr. Jeffrey Brubacher.

Cannabis was legalized in all Canadian provinces and territories on October 17, 2018. The main psychoactive compound found in marijuana, THC produces effects such as dizziness, memory loss and problems with concentration. 

"In general, the type of impairment that goes hand-in-hand with cannabis is impaired attention.”

The legal THC limit for drivers in the country is less than two nanograms (ng) per millilitre of blood. Exceeding that limit may put a driver at risk of decreased judgement and driving abilities. 

“High THC levels in the bloodstream may impact the brain and can affect someone’s capacity for sustained and divided attention, along with their fine motor skills,” says Brubacher. “Drivers may have difficulty navigating and driving at the same time, as well as staying between the lines and braking quickly should, for example, someone step out in front of them.” 

Dr. Jeffrey Brubacher is the director of the Emergency Medicine Research Program at VCHRI and an emergency physician at Vancouver General Hospital. He is also the director of the Road Safety and Public Health Research lab and an associate professor in the Department of Emergency Medicine at the University of British Columbia.

Brubacher’s study, published in The New England Journal of Medicine, reviewed the hospital records of drivers treated in four B.C.-based trauma centres following a motor vehicle collision between January 2013 and March 2020 — before and after legalization in 2018. 

“We only included moderately injured drivers, as their condition warranted a blood test as part of their clinical assessment, which is how we could account for the presence or concentration of THC levels in their bloodstreams,” explains Brubacher. 

Levels of THC above the two ng per millilitre limit were detected in blood samples of 3.8 per cent of the drivers reviewed in Brubacher’s study before legalization. That number jumped to 8.6 per cent after legalization. Most of this increase occurred in males. Similarly, drivers with THC levels above five ng per millilitre went from 1.1 per cent before legalization to 3.5 per cent afterwards. 

THC was detected in 9.2 per cent of drivers prior to legalization and 17.9 per cent after legalization. 

Crashes involving drivers with unsafe THC levels doubled after legalization   

The magnitude of the increase in drivers with THC levels above two ng per millilitre surprised Brubacher, as did the fact that drivers aged 50 and older were 5.18 times more likely to be part of this group.
 
“Most of the research into marijuana consumption has focused on younger adults, as they tend to be a demographic that uses cannabis and may also be more open to participating in studies,” says Brubacher.

“I suspect that more older adults may have felt comfortable returning to recreational use after legalization or are using it for medicinal purposes.”

Brubacher cautions, however, that the cognitive and psychomotor skills needed for safe driving tend to decline with age. Older adults are also more likely to take medications with potential side effects that could be compounded by THC, he adds. 

These risk factors elevate the odds that adults aged 50 and older could end up crashing while driving high and sustaining serious injuries, says Brubacher. The duration of their stay in hospital could be longer, and the potential for long-term health implications — such as chronic pain or disability — after a crash greater.

“People get frailer cognitively and physically as they age, which can make older adults more sensitive to the effects of THC and more likely to experience serious consequences from a crash. This is an emerging risk that warrants further research.”
 

Researchers

Jeff Brubacher

Related Articles

What matters to older adults in physical activity research

Ask an expert: How can I better communicate with older adults living with a communication disorder?

Focusing on WhatMatters in dementia care

Share:

  • Facebook
  • Linkedin
  • Twitter
  • Email

Related Research Centres/Programs

Emergency Medicine Research Program

Get the latest research headlines in your inbox

Subscribe

Recent News and Stories

Type
Announcement

Celebrating the life and distinguished career of Dr. Marcel Dvorak

May 14, 2025
Type
Stories

More equitable representation needed in Parkinson’s research

May 9, 2025 parkinsons, patient engagement, women
Type
Stories

Gamified stroke recovery improves arm function

May 8, 2025 stroke, rehabilitation
See more news

Get updates!

Join our newsletter mailing list to stay up to date on features and releases.

Subscribe

Quick Links

  • News and Stories
  • Careers
  • Events
  • Media Enquiries

Follow Us

  • LinkedIn
  • X
  • YouTube

© 2025 VCHRI. All rights reserved.

  • Contact
  • Privacy Policy