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Peak versus off-peak effects of cannabis: Impacts on driving performance

Gary Gaffney

G. Gaffney1,2, G. Milavetz1,3, T. Brown1, A. Spurgin1,3, R.J. Johnson4. 1National Advanced Driving Simulator, University of Iowa, United States; 2Carver College of Medicine, University of Iowa, United States; 3College of Pharmacy, University of Iowa, United States; 4Advanced Brain Monitoring–San Diego, United States

Background: Medicinal cannabis is available in 23 states and Washington D.C. and decriminalized for recreational use by adults in four states. This increased availability has called into question public health issues like the impact of more cannabis-impaired drivers on the road. A need exists for the establishment of an evidence-based understanding of the time-impairment profile of cannabis effects.

Methods: Using a quarter-cab driving simulator and a portable EEG system, effects of cannabis on brain electrical activity and driving performance were investigated in occasional cannabis users (n=20) under placebo control. Data collection for EEG began at one hour post dose and for driving at two hours post dose. Driving performance measures were collected in urban, interstate and rural driving environments at night. Additionally driving performance was compared to previously published data during peak drug effect.

Results: Changes in brain activity after administration were observed compared to placebo. Analysis of general driving performance measures showed no statistically significant differences between active and placebo doses two hours post dose. Statistically significant effects were found for these measures in a prior study with the same dose of equipotent cannabis, and same driving environment starting at 25-minutes post dose.

Conclusions: This study suggest that the acute effects of THC on driving performance measures are sensitive to time from administration and other pharmacokinetic parameters. Despite lingering effects observable in the EEG, effects on driving performance may not persist as long as previously thought. Further pharmacodynamic study is needed to better understand the time-effect profile of the acute cannabis impairment on driving. This research was support by an SBIR from the National Institutes on Drug Abuse.

Abstract Year: 
2015
Abstract Region: 
North America
Abstract Country: 
United States
Abstract Category: 
Prevention