A study of driving impairment and cannabis use found that frequent cannabis users did not demonstrate impaired driving performance after at least 48 hours of abstinence. The findings published in Psychopharmacology have implications for more effective cannabis and driving policies. Enforcing cannabis and driving laws is challenging, because there the psychoactive compound Delta-9 tetrahydrocannabinol (THC) can be detected in blood and urine for weeks after use.
The research team from the Center for Medicinal Cannabis Research (CMCR) at the University of California San Diego School of Medicine analyzed data from two studies to explore the association between driving simulator performance, cannabis use history, and demographic factors. Study I assessed driving simulator performance in a sample of 191 healthy cannabis users. They reflected a broad range of use levels and had abstained for at least 48 hours before the simulations. Study II compared a subset of 18 of the highest cannabis use intensity users and 12 non-cannabis users from Study I. The main outcome of both Study I and II was the Composite Drive Score (CDS), which is a global measure of driving performance that assesses key driving-related variables like standard deviation of lateral position.
The researchers did not find evidence of reduced driving ability in cannabis users who had abstained for at least two days. They did not observe any relationship between CDS, its subtests, measures of cannabis use history, time of abstinence, blood THC concentrations, or demographic variables in Study I. The team observed no differences in CDS or subtest performance between frequent cannabis users and the non-using comparison group in Study II.
The study contributes to a growing body of evidence that relying on blood THC concentrations does not offer reliable and accurate cannabis intoxication testing. This study highlights the need for future research on the short-term residual effects on driving performance when engaging in more complex driving tasks.
Sources: Eureka News Alert, Psychopharmacology