CBD Up to 1,500 mg Did Not Impair Driving or Cognitive Function in a Crossover Trial
Oral CBD at doses up to 1,500 mg did not impair simulated driving performance or cognitive function compared to placebo, though CBD persisted in plasma for over 4 weeks at the highest dose.
Quick Facts
What This Study Found
Non-inferiority analyses established that CBD at 15, 300, and 1,500 mg did not impair driving performance beyond a threshold equivalent to 0.05% blood alcohol. CBD did not induce feelings of intoxication or impair cognitive function. Unexpectedly, CBD at 1,500 mg persisted in plasma for more than 4 weeks.
Key Numbers
17 participants; 4 CBD doses (placebo, 15, 300, 1500 mg); non-inferiority threshold: 0.05% BAC equivalent; CBD detectable in plasma >4 weeks at 1500 mg
How They Did This
Double-blind, placebo-controlled, crossover RCT in 17 healthy adults. Four sessions: placebo, 15 mg, 300 mg, or 1,500 mg oral CBD. Simulated driving assessed at ~45-75 and ~210-240 minutes post-treatment. Primary outcome: standard deviation of lateral position (SDLP).
Why This Research Matters
CBD is widely consumed in both prescription and non-prescription products, yet its effects on safety-sensitive tasks have been under scrutiny. This study provides reassuring evidence that even high doses do not impair driving.
The Bigger Picture
While THC clearly impairs driving, this study adds to evidence that CBD does not. The long plasma persistence of high-dose CBD may have implications for drug testing but does not appear to affect function.
What This Study Doesn't Tell Us
Small sample (n=17). Single-dose acute administration only. Simulated driving, not real-world. May not generalize to chronic CBD users or those taking CBD with other medications.
Questions This Raises
- ?Could the prolonged plasma persistence of CBD cause false-positive drug tests?
- ?Would chronic high-dose CBD use produce different driving effects than acute dosing?
Trust & Context
- Key Stat:
- No driving impairment at any CBD dose up to 1,500 mg
- Evidence Grade:
- Well-designed double-blind crossover RCT with validated driving measures, but small sample size (n=17).
- Study Age:
- Published in 2022
- Original Title:
- Effects of cannabidiol on simulated driving and cognitive performance: A dose-ranging randomised controlled trial.
- Published In:
- Journal of psychopharmacology (Oxford, England), 36(12), 1338-1349 (2022)
- Authors:
- McCartney, Danielle(22), Suraev, Anastasia S(4), Doohan, Peter T(7), Irwin, Christopher, Kevin, Richard C, Grunstein, Ronald R, Hoyos, Camilla M, McGregor, Iain S
- Database ID:
- RTHC-04052
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Can you drive after taking CBD?
This study found oral CBD at doses up to 1,500 mg did not impair simulated driving performance or cause feelings of intoxication. Driving performance was not worse than the equivalent of 0.05% blood alcohol at any dose.
How long does CBD stay in your system?
At 1,500 mg, CBD was detectable in plasma for more than 4 weeks. Lower doses cleared faster. This prolonged presence did not affect driving performance or cognition.
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Cite This Study
https://rethinkthc.com/research/RTHC-04052APA
McCartney, Danielle; Suraev, Anastasia S; Doohan, Peter T; Irwin, Christopher; Kevin, Richard C; Grunstein, Ronald R; Hoyos, Camilla M; McGregor, Iain S. (2022). Effects of cannabidiol on simulated driving and cognitive performance: A dose-ranging randomised controlled trial.. Journal of psychopharmacology (Oxford, England), 36(12), 1338-1349. https://doi.org/10.1177/02698811221095356
MLA
McCartney, Danielle, et al. "Effects of cannabidiol on simulated driving and cognitive performance: A dose-ranging randomised controlled trial.." Journal of psychopharmacology (Oxford, 2022. https://doi.org/10.1177/02698811221095356
RethinkTHC
RethinkTHC Research Database. "Effects of cannabidiol on simulated driving and cognitive pe..." RTHC-04052. Retrieved from https://rethinkthc.com/research/mccartney-2022-effects-of-cannabidiol-on
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.