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Smoking CBD-Rich Marijuana Has ‘No Significant Impact’ On Driving Ability, Study Finds

January 21, 2022

A study found that marijuana did not impair driving ability and that users can consume the drug and still operate a vehicle safely. The researchers also determined that while marijuana may increase heart rate within minutes of consumption, it can cause a decrease in heart rate after regular use.

A pilot study conducted in Switzerland is the first of its kind to prove without a doubt that cannabinoids can affect real-world behavior even outside of the laboratory. Thirty-three volunteers consumed joints containing either 500 mg of CBD-rich marijuana or 500 mg of a THC-free placebo and then underwent various sobriety tests.

Cannabis is becoming more and more prominent in Switzerland, so researchers wanted to investigate if CBD-based smoking cessation products have the same driving impairment effects as regular cigarettes.

According to three researchers from the Institute of Forensic Medicine at the University of Bern, the “purpose of the current study was to inform recommendations for warnings on marijuana-based tobacco substitutes, commonly known as ‘Snax.’” The study highlighted the ad advantages that come with consuming such products.

“To the best of our knowledge, the current study is one of the first to investigate the potential impact of smoking CBD-rich marijuana for road safety,” they concluded.

The study’s main result was no differences in the effects of CBD-dominate marijuana and placebo on performance and stress reaction time, motor behavior, and concentration.

To obtain data regarding the effects of THC, blood samples were drawn from participants after smoking and after their assessments. The cannabinoids in their systems were then quantified to determine if CBD affected cannabinoid measurements.

The participants in the study were 19 male and 14 female subjects (average age of 31 years) who flipped a coin to determine whether they would receive a placebo or CBD-based marijuana. This procedure was conducted twice, with each participant being given the opposite treatment on the second day.

Statistical analysis revealed three distinct groups of users: those who consumed CBD versus placebo, those who were women versus men, and those who had already tried CBD in the past versus those trying it for the first time.

The assessment of the driver’s psychological state consisted of three tests designed to measure and examine the attitudes relevant to road safety. The examination was intended to aid reliable decision-making regarding an individual’s fitness to drive. To test their ability to react under complex stimulus conditions, participants in the first experiment took a reaction time test, which involved pressing buttons as quickly as possible after seeing a light turn on. Participants who reacted more earned soon higher scores. Participants then took a mental reaction test. They were shown geometric shapes and had to compare that shape with four other shapes, choosing the one that was identical to the original shape.

To determine the range of stimulus frequencies that stressed participants, researchers put them in a stressful situation and exposed them to various stimuli. By observing participants’ behavior under varying degrees of stress, researchers learned the threshold of stimulus frequencies that triggered the highest level of exhaustion.

The study results revealed that CBD did not produce any statistically significant differences in comparison to the placebo. The researchers found no significant difference in the outcome between male and female participants, nor was there a difference between the first and second trials.

The Cognition test, where the participant rated one geometric figure against four other geometric figures, also showed no significant differences between cannabis and placebo or between men and women. The first trial also had no significant differences compared to the second trial.

To assess one’s fitness to drive, three standard tests were given for balance and coordination. The tests mirror those used by drug recognition experts. “These tests are regularly used in Switzerland by trained medical personnel on behalf of the police to determine neurological deficits after substance misuse and possible intoxication of persons suspected of impaired driving,” the study states.

To test for balance and an internal clock, participants had to stand with their arms out and eyes closed. They were required to open their eyes within 30 seconds after the examiner told them to do so, and the examiner recorded when they opened their eyes. Differences in the amount of time to balance the board between placebo and CBD groups were not statistically significant. Still, the differences were within the normal range of 20 to 45 seconds. Regardless of whether the CBD or placebo joint was smoked, all study participants could maintain a secure balance.

Next, the commonly seen finger-to-nose test was ordered. After the test was completed, 32 out of 33 participants touched their noses when they smoked a joint containing CBD and also when they smoked a placebo joint – regardless of whether it contained CBD or not. The experiment met with mixed results. “After” researchers had administered the CBD joint, “all but two of the participants managed to miss the tip of their nose.” The sample size for this study was small, allowing for 15 people in each group. Even so, only five participants correctly followed instructions to alternate arms, left-right-left-right-right-left: three from the CBD group and twice from participants who smoked the placebo joint.

The subjects’ blood tests revealed that they all had THC in their system, above the legal limit. Despite this, there were no significant differences in vital signs for those who were smoking high CBD marijuana as compared to low-CBD marijuana. Researchers determined that the subjects did not have any harmful side effects from smoking the high CBD content marijuana.

“Although free THC concentrations reached levels that were considered to cause symptoms of impairment in other studies in which THC-rich marijuana was smoked, no signs of impairment were observed in the current study,” the researchers wrote. “These findings suggest that higher CBD concentrations caused a negative allosteric effect in the endocannabinoid system, preventing the formation of such symptoms.”

The researchers who conducted the study recommend that consumers refrain from driving for a few hours after smoking marijuana, even though there were no signs of impairment. In a smoker’s body, CBD can affect THC concentration levels, and THC causes impairment. Users should also know their legal driving limit when consuming CBD products.

This conclusion is similar to the findings of a study conducted by the University of Sydney. Other studies have also come to the same conclusion regarding THC concentration and the risk of driving. This information is supported by an official report from the Michigan Impaired Driving Safety Commission, which concluded that there should not be a per se limit on THC concentration in the blood. It can only be determined whether a driver is impaired with a roadside sobriety test(s).

A 2019 study revealed that driving while under the influence of marijuana is not as big a problem as previously thought. Drivers with THC levels of 2 to 5ng/ml were not statistically more likely to be involved in an accident than those without THC.

A Congressional Research Service Report published in February 2019, employing statistics from the National Highway Traffic Safety Administration and the Federal Bureau of Investigation, found that marijuana consumption reduces reaction time and motor coordination. However, it added that “studies of the impact of marijuana use on a driver’s risk of being involved in a crash have produced conflicting results, with some studies finding little or no increased risk of a crash from marijuana usage.