How Does Cannabis Affect Driving?
大麻如何影响驾驶？
A new JAMA editorial breaks down a study measuring driving impairment in participants who received doses of THC, CBD, or a mix.
Driving under the influence of alcohol is a major cause of preventable death, and one that is well understood. But, while driving under the influence of cannabis is estimated to account for thousands of US road traffic deaths each year, little is known about how much cannabis impairs a driver. As cannabis use increases across the country, and as more states legalize medical and recreational cannabis, this question is becoming more and more important.
Now, a new JAMA editorial, co-authored by a School of Public Health researcher, breaks down a study measuring driving impairment in participants who received doses of tetrahydrocannabinol (THC), cannabidiol (CBD), or a mix of THC and CBD. The study found that a small dose of THC or of THC and CBD together impaired driving, but not a small dose of CBD—although the question of larger CBD doses was left open.
“These findings challenge the myth that CBD ameliorates the psychoactive/psychomotor effects of THC,” write Thomas B. Cole, associate editor of JAMA, and Richard Saitz, professor and chair of community health sciences and also a JAMA associate editor.
However, Saitz and Cole focus their editorial on discussing the difficulty of studying cannabis impairment, and the limitations of the study—including a dose size on the very low end of recommended medical use, and the fact that recreational cannabis products often lack accurate quantification of the THC, CBD, and other cannabinoids they contain.
“While the findings from this trial do not support the conclusion that it is safe to drive after consuming CBD, it is clear that THC did impair driving performance,” they write, and “cannabis products containing equal parts CBD and THC are no less impairing than products containing THC alone.”
Read the editorial here.