Format

Send to

Choose Destination
J Appl Toxicol. 2016 Nov;36(11):1418-29. doi: 10.1002/jat.3295. Epub 2016 Feb 18.

Cannabis effects on driving longitudinal control with and without alcohol.

Author information

1
Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, NIH, 251 Bayview Boulevard Street, 200 Rm 05A721, Baltimore, MD, USA.
2
National Advanced Driving Simulator, University of Iowa, 2401 Oakdale Boulevard, Iowa City, IA, USA.
3
College of Pharmacy, University of Iowa, Iowa City, IA, USA.
4
VariableSolutions, USA.
5
Department of Psychiatry, University of Maryland School of Medicine, Baltimore, MD, USA.
6
Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
7
Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, NIH, 251 Bayview Boulevard Street, 200 Rm 05A721, Baltimore, MD, USA. mhuestis@intra.nida.nih.gov.

Abstract

Although evidence suggests cannabis impairs driving, its driving-performance effects are not fully characterized. We aimed to establish cannabis' effects on driving longitudinal control (with and without alcohol, drivers' most common drug combination) relative to psychoactive ∆(9) -tetrahydrocannabinol (THC) blood concentrations. Current occasional (≥1×/last 3 months, ≤3 days per week) cannabis smokers drank placebo or low-dose alcohol, and inhaled 500 mg placebo, low (2.9%), or high (6.7%) THC vaporized cannabis over 10 min ad libitum in separate sessions (within-subject, six conditions). Participants drove (National Advanced Driving Simulator, University of Iowa) simulated drives 0.5-1.3 h post-inhalation. Blood and breath alcohol samples were collected before (0.17 and 0.42 h) and after (1.4 and 2.3 h) driving. We evaluated the mean speed (relative to limit), standard deviation (SD) of speed, percent time spent >10% above/below the speed limit (percent speed high/percent speed low), longitudinal acceleration, and ability to maintain headway relative to a lead vehicle (headway maintenance) against blood THC and breath alcohol concentrations (BrAC). In N=18 completing drivers, THC was associated with a decreased mean speed, increased percent speed low and increased mean following distance during headway maintenance. BrAC was associated with increased SD speed and increased percent speed high, whereas THC was not. Neither was associated with altered longitudinal acceleration. A less-than-additive THC*BrAC interaction was detected in percent speed high (considering only non-zero data and excluding an outlying drive event), suggesting cannabis mitigated drivers' tendency to drive faster with alcohol. Cannabis was associated with slower driving and greater headway, suggesting a possible awareness of impairment and attempt to compensate.

KEYWORDS:

THC; alcohol; blood; cannabis; driving; speed

PMID:
26889769
DOI:
10.1002/jat.3295
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center