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Psychopharmacology (Berl). 2019 May 1. doi: 10.1007/s00213-019-05246-8. [Epub ahead of print]

Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition.

Author information

1
Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, New South Wales, Australia.
2
Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia.
3
Faculty of Medicine, Central Clinical School, The University of Sydney, Sydney, New South Wales, Australia.
4
The Langton Centre, Drug and Alcohol Services, South East Sydney Local Health District, NSW Health, Sydney, New South Wales, Australia.
5
Faculty of Science, School of Psychology, The University of Sydney, Sydney, New South Wales, Australia.
6
Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, The Netherlands.
7
Johns Hopkins University School of Medicine, Baltimore, MD, USA.
8
School of Allied Health Sciences, Griffith University, Gold Coast, Australia.
9
Drug Health Services, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.
10
Lambert Initiative for Cannabinoid Therapeutics, The University of Sydney, Sydney, New South Wales, Australia. iain.mcgregor@sydney.edu.au.
11
Brain and Mind Centre, The University of Sydney, Sydney, New South Wales, Australia. iain.mcgregor@sydney.edu.au.
12
Faculty of Science, School of Psychology, The University of Sydney, Sydney, New South Wales, Australia. iain.mcgregor@sydney.edu.au.

Abstract

BACKGROUND:

The main psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC), can impair driving performance. Cannabidiol (CBD), a non-intoxicating cannabis component, is thought to mitigate certain adverse effects of THC. It is possible then that cannabis containing equivalent CBD and THC will differentially affect driving and cognition relative to THC-dominant cannabis.

AIMS:

The present study investigated and compared the effects of THC-dominant and THC/CBD equivalent cannabis on simulated driving and cognitive performance.

METHODS:

In a randomized, double-blind, within-subjects crossover design, healthy volunteers (n = 14) with a history of light cannabis use attended three outpatient experimental test sessions in which simulated driving and cognitive performance were assessed at two timepoints (20-60 min and 200-240 min) following vaporization of 125 mg THC-dominant (11% THC; < 1% CBD), THC/CBD equivalent (11% THC, 11% CBD), or placebo (< 1% THC/CBD) cannabis.

RESULTS/OUTCOMES:

Both active cannabis types increased lane weaving during a car-following task but had little effect on other driving performance measures. Active cannabis types impaired performance on the Digit Symbol Substitution Task (DSST), Divided Attention Task (DAT) and Paced Auditory Serial Addition Task (PASAT) with impairment on the latter two tasks worse with THC/CBD equivalent cannabis. Subjective drug effects (e.g., "stoned") and confidence in driving ability did not vary with CBD content. Peak plasma THC concentrations were higher following THC/CBD equivalent cannabis relative to THC-dominant cannabis, suggesting a possible pharmacokinetic interaction.

CONCLUSIONS/INTERPRETATION:

Cannabis containing equivalent concentrations of CBD and THC appears no less impairing than THC-dominant cannabis, and in some circumstances, CBD may actually exacerbate THC-induced impairment.

KEYWORDS:

CBD; Cannabidiol; Cannabis; Cognition; Driving; THC; Tetrahydrocannabinol

PMID:
31044290
DOI:
10.1007/s00213-019-05246-8

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