CannaTrials adheres to evidence-based medicine – making statements based on medical evidence.

This page is excerpted and quoted from the National Academies of Science, Engineering, and Medicine.    A Committee of over 40 experts, researchers, and reviewers in The Health and Medicine Division published a 486 page report in 2017 entitled “The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research.
If you would like to access the entire report you may do so by clicking this link.

Medical Marijuana and Motor Vehicle Crashes

“In 2011, motor vehicle crashes (MVCs) were the leading cause of death among U.S. adolescents and adults ages 16 to 25 years (NHTSA, 2015). Among all age groups, MVCs occurring in 2014 resulted in more than 32,000 fatalities and more than 2 million nonfatal injuries in the United States (CDC, 2016a; NHTSA, 2016).5 Nationally, the combined medical and work loss costs associated with these fatal and nonfatal injuries is substantial at $44 and $51.3 billion, respectively (Bergen et al., 2014; CDC, 2015).6

In 2014, 3.2 percent of individuals ages 16 to 25 years reported driving while intoxicated by cannabis (Azofeifa et al., 2015), and the prevalence of THC metabolites detected in the blood or oral fluids of weekend nighttime drivers participating in the National Roadside Survey rose from 8.6 percent in 2007 to 12.6 percent in 2013–2014 (Berning et al., 2015). Given the public health burden of MVC-related morbidity and mortality and the presence of cannabis use and intoxication while driving, there is a need for research to understand the effects of cannabis use on the incidence and severity of motor vehicle crashes and the safety and performance of drivers.

Two important methodological limitations of Rogeberg and Elvik (2016) were noted by other researchers (Gjerde and Morland, 2016). First, DUIC may have not just referred to acute intoxication. Indeed, many of the studies considered in this review scored case and control counts as positive using criteria that would also be satisfied by drivers with recent or regular cannabis use but who were neither intoxicated nor impaired while driving (Gjerde and Morland, 2016). Moreover, the association between THC levels in blood and either acute intoxication or driving impairment remains a subject of controversy, and it could represent an important limitation in the interpretation of findings in culpability studies based on blood THC levels (Desrosiers et al., 2014; Khiabani et al., 2006; Logan et al., 2016; Menetrey et al., 2005; Papafotiou et al., 2005). Second, 3 of the 21 studies used different methods to assess cases and controls, which may lead to a non-differential misclassification of exposure. A missing component in this review is a better determination of the dose at which driving becomes sufficiently unsafe as to increase MVC risk. Finally, Rogeberg and Elvik (2016) did not provide evidence from cohort studies to address DUIC in MVC.

Simulator studies were also not included in Rogeberg and Elvik (2016). Some laboratory and simulator studies that have examined the effects of acute cannabis intoxication on driving performance have found that the psychomotor skills necessary for safe driving become increasingly impaired at higher doses of cannabis (Sewell et al., 2009). While these experiments may have high internal validity regarding dose-related effects on psychomotor performance, they do not necessarily reflect the complex nature of driving ability and MVC risk attributed to DUIC in a real-world scenario. Epidemiological studies of MVC in populations may help to address these limitations and are the only reasonable and ethical alternative to controlled experiments outside the laboratory. However, cannabis smokers have demographic characteristics that are similar to those of other groups with a high crash risk, including youth, males, and those with a high prevalence of drugged and drunk driving (Bergeron and Paquette, 2014; Richer and Bergeron, 2009). In particular, confounding or effect modification with alcohol is an important driver-related factor that needs to be better taken into account. The bulk of the evidence available describing the association between DUIC and MVCs comes from case-control studies that evaluate the odds of a MVC by DUIC status and from culpability studies which evaluate the odds of culpability in drivers involved in collisions by DUIC status.

CONCLUSION 9-3 There is substantial evidence of a statistical association between cannabis use and increased risk of motor vehicle crashes. [1]

[1] The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research | The National Academies Press. 2017. Pages 227-230. Download the complete 486 page report.

**Important Note:  On many of the health conditions studied by NAS, there was no conclusive evidence of cannabis effectiveness from the study results they reviewed.  The authors included a long section on “research gaps.

It is the Vision and Mission of CannaTrials to fill in some of these research gaps with cannabis clinical trials using specific medical marijuana formulations and testing them in a research protocol with local patients, physicians, processors and dispensaries.  If you are interested in participating in a clinical trial, and helping improve scientific knowledge about health effects of cannabis, please click one of the buttons below on this page.

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