A two-year study found that at least 50% of subjects who smoked cannabis with THC in a randomized clinical trial had a significantly diminished ability to drive compared to subjects who took a placebo cigarette.
Before this study, there were a number of small studies that examined learning, attention, and speed of processing under the influence of cannabis.
“This groundbreaking research indicates that cannabis use does impair driving ability, but factors differ from alcohol,” California State Assemblymember Tom Lackey said.
The simulation required participants to maintain their lane position and speed in a straight roadway while responding to a divided attention task on an iPad on the dashboard.
Their performance was measured by several different variables, such as the measures of variation of lateral position and speed, and the number of correct divided attention stimuli identified while driving.
There were several main takeaways from this study.
Additionally, performance didn’t differ between the two different levels of cannabis content, suggesting that the levels of cannabis intake resulted in comparable levels of highness.
The impairment lasted until about four and a half hours for the entire group, with some individuals feeling less impaired after three and a half hours.
Generally, the paper noted there was no relationship between THC blood concentration and impairment.
Furthermore, the group with the highest cannabis usage in the past six months had significantly higher THC blood concentrations after smoking but didn’t perform worse than those with lower THC blood concentrations; this suggests behavioral tolerance.
“People who are regular users believe that because they use all of the time, they don’t get as stoned with the same amount of THC as someone who’s an infrequent user, and we actually found that is true,” Marcotte explained.
This finding shows that when it comes to policing cannabis intake and driving, different laws may have to be made since impairment can’t be deduced by cannabis content in cigarettes, behavioral tolerance, or THC blood concentrations.
Marcotte added that the study provides valuable information to users, warning them that they are not always the best judges of their ability to drive.
“An important thing for users to know is because you’re an experienced user does not necessarily mean you’re going to be less impaired.
Subjects were told to get to a level of highness as they would casually at home, meaning that the study didn’t address controlled dosing or very elevated levels of highness.
“We have a new study starting up to look at the combination of alcohol and cannabis, and seeing whether you can be an alcohol level below the legal limit and officially, you’re fine at least in terms of the blood levels.
Fitzgerald elaborated that they’re interested in studying other methods of ingesting cannabis, such as oral routes like gummies and edibles in addition to highly concentrated forms like vapes and concentrated butane hash oil .
To see more of the research done by the CMCR, you can find their website here.