Studies show that the intoxicating component of cannabis, tetrahydrocannabinol (THC), can cause dose-dependent sensory and perceptual changes, and lead to acute impairment of cognitive and psychomotor performance. This may compromise the ability to perform tasks such as driving by increasing the risk of error, accident, and injury.
Other research indicates that cannabidiol (CBD), a non-intoxicating component of cannabis, does not impair cognition, psychomotor skills, or driving ability even at high doses. Some research suggests, however, that CBD can inhibit the metabolism of THC when taken orally, potentially increasing the magnitude and duration of THC-related impairment.
In the current study, researchers investigated whether taking cannabis oil containing both THC and CBD for insomnia affects driving ability and cognitive and psychomotor skills a day later. To do so, they recruited 20 adults with insomnia who were an average age of 46 years old. Three-quarters of participants had either never taken cannabis before or had taken the substance less than 10 times throughout their lives. None had cannabinoid products in the previous three months, as verified by a urinary drug screen.
Participants took part in two 24-hour overnight lab visits. On one night, they received 2 ml of medicinal cannabis oil containing 10 mg THC and 200 mg CBD. They took a placebo on the other night. On the morning following each treatment- around 9-11 hours after taking the cannabis oil- participants completed 28 cognitive tasks that tested for various cognitive functions, including attention, memory, and executive functioning. They also participated in a 30-minute simulated driving scenario.
Ultimately, the researchers found that taking cannabis oil did not significantly affect cognitive or psychomotor abilities. While cannabis oil was linked to a slight decrease in executive function, the reported difference was small and not clinically meaningful. Cannabis oil appeared not to affect driving ability.
There are some limitations to the findings. Owing to the study design, the researchers could not assess the individual effects of THC and CBD, and due to the small sample size, their findings may have limited statistical power. Additionally, as they only examined effects from a single dose, the effects of repeated dosing remain unknown.
Sources: PsyPost, Psychopharmacology