Driving

While research has shown that cannabis, and its major intoxicating ingredient – THC, impair car driving performance, the influence of cannabidiol (CBD) (alone) has not been studied. Findings from several investigations suggest that, unlike THC, CBD is non-intoxicating and does not impair cognitive function. However, given the potential harms associated with road traffic accidents and the increasing use of CBD (among both clinical and non-clinical populations) research clarifying its effect on driving performance is warranted. This study will investigate the effect of acute, oral CBD treatment (at three different doses) on simulated driving performance using a crossover design.

This study has completed recruitment and data collection. This page will be updated with the results of the study.

This is a collaboration between The Lambert Initiative at the University of Sydney and the Woolcock Institute of Medical Research.

Principle Investigator:         Professor Iain McGregor (LI, University of Sydney)

Project Coordinator:          Dr Danielle McCartney (LI, University of Sydney)

                                                  Email: danielle.mccartney@sydney.edu.au

                                              Telephone: 02 9351 0783.     

Publication: https://link.springer.com/article/10.1007/s00213-019-05246-8

This study compared the effects of standard high-THC cannabis, balanced THC/CBD cannabis, and placebo cannabis on simulated driving and cognitive performance. In a randomized, double-blind, crossover design, 14 healthy volunteers with a history of light cannabis use attended 3 outpatient experimental test sessions in which simulated driving and cognitive performance were assessed.

Results: The type of impairment seen with high THC cannabis involving greater lane-weaving. However, on other measures intoxicated participants were somewhat safer, tending to leave a larger gap between them and the car in front compared and showing no tendency to speed.

Contrary to prediction, the study found that the addition of CBD did not reduce feelings of intoxication, nor did it lessen driving impairment compared with standard high-THC cannabis. In some circumstances, the study found that CBD exacerbated THC-induced impairment.

This was a collaboration between The Lambert Initiative at the University of Sydney, Royal Prince Alfred Hospital and Tilray.

Chief Investigators: Professor Iain McGregor (Lambert Initiative, University of Sydney)

Project Coordinator: Thomas Arkell (Lambert Initiative, University of Sydney)

Experimental studies indicate that cannabis causes dose-dependent impairment in driving performance and associated cognitive function, however these studies have only considered the effects of the main intoxicating component of cannabis, THC. Here we will examine in a four way crossover design trial, whether vaporized medicinal cannabis containing a 1:1 ratio of THC and CBD impairs driving in the same way as cannabis containing an equivalent amount of THC with no CBD, as well as effects of vaporised CBD only (no THC) on performance. The novel study will examine real-world driving performance at various time points following consumption and examine driving in both urban and highway environments.

This is a collaboration between The Lambert Initiative at the University of Sydney, Maastricht University and Bedrocan International.

Chief Investigators: Professor Jan Ramaekers (Maastricht University)

Project Coordinator: Thomas Arkell (Lambert Initiative, University of Sydney)

Publication:  https://doi.org/10.1002/dta.2687

This study examined the accuracy of two of the most commonly used mobile drug testing devices (Securetec DrugWipe 5s and Draeger DrugTest 5000) in detecting oral fluid tetrahydrocannabinol (THC). Using a randomized, placebo controlled, double‐blind and crossover design, 14 healthy volunteers with a history of occasional cannabis use (<2x/week) attended 3 outpatient experimental test sessions in which they vaporised two different cannabis types (THC dominant; THC/CBD equivalent) and placebo. Oral fluid tests were performed at fixed intervals over 3 hours, yielding a total of over 300 tests. Both devices had a detection limit of 10 ng/mL THC.

Results: 

This study found a relatively high occurrence of false positive and false negative results. 5% of DW5s test results were false positives and 16% false negatives. For the DT5000, 10% of test results were false positives and 9% false negatives. By 180 min, all samples contained less than 10 ng/mL THC. Neither device demonstrated the recommended >80% sensitivity, specificity and accuracy.

This was a collaboration between The Lambert Initiative at the University of Sydney, Royal Prince Alfred Hospital and Tilray.

Chief Investigators: Professor Iain McGregor (Lambert Initiative, University of Sydney)

Project Coordinator: Thomas Arkell (Lambert Initiative, University of Sydney)