National Academies Issues Report on Health Effects of Cannabis

Earlier this year, the National Academies of Science, Engineering, and Medicine (NASEM) released a report on the health effects of cannabis and cannabinoids. This report—which features some 100 conclusions related to the health effects of recreational and therapeutic use of the drug and related products—offers the most comprehensive analysis of available evidence since 1999.

“For years, the landscape of marijuana use has been rapidly shifting as more and more states are legalizing cannabis for the treatment of medical conditions and recreational use,” Marie McCormick, M.D., Sc.D., chair of the 16-person committee who wrote the report, said in a press statement. “As laws and policies continue to change, research must also.”

As such, in addition to offering conclusions on the health effects of cannabis, the committee included in the report four broad recommendations to improve cannabis-related research moving forward. The recommendations included strategies to tackle existing research gaps, improve existing research standards and benchmarks, strengthen federal and state-based public health surveillance, and address regulatory barriers.

“The new report is based on reviews of research on both the cannabis plant itself and its constituents, but its conclusions are substantially similar to the 1999 report,” Nora Volkow, M.D., director of the National Institute on Drug Abuse (NIDA), wrote on her blog following the release of the report.

“While cannabis use, particularly smoked cannabis, poses some long-term health and safety risks, there is evidence that cannabis or cannabinoids can treat certain medical conditions, which include nausea and vomiting from chemotherapy, spasticity from multiple sclerosis, and pain.”

Volkow, who was not part of the NASEM committee, continued, “NIDA strongly agrees with the report’s finding that there are impediments to performing quality research on cannabis and cannabinoids and that there is a need to address these impediments so that researchers can draw more confident conclusions.”

The report found that the strongest evidence for the therapeutic value of cannabis or cannabinoids continues to be limited to certain types of chronic pain and nausea/appetite stimulation. Even in these instances, the report noted that the evidence of therapeutic value comes from studies that used isolated cannabinoid formulations and not the cannabis plant, which contains hundreds of varied chemicals.

Other purported health benefits such as controlling tics in Tourette’s syndrome, improving motor problems in neurodegenerative diseases, and reducing anxiety disorders remain unproven.

In addition, “there are currently no consistent quality controls, no assurances that patients are informed about side effects, and unclear recommendations about dosing and route of administration,” Volkow wrote. “It is important for people to understand the range of effects produced by cannabis as they weigh the risks and benefits for treating their health conditions with products from state dispensaries,” she continued.

Sachin Patel, M.D., Ph.D., the James G. Blakemore Chair and Associate Professor of Psychiatry and Behavioral Sciences at Vanderbilt University Medical Center, who was one of the members of the NASEM committee tasked with creating the report, acknowledged that while gaps still remain as to whether cannabis and related compounds are medically useful, there have been notable scientific advances in this area of research.

“There has been a dramatic change in our understanding of how cannabis acts on the brain, and the role that specific cannabinoid molecules and their receptors play,” he told Psychiatric News.

In March, Patel and his lab reported findings that suggested augmenting or depleting 2-arachidonoylglycerol (2-AG)—a naturally occurring cannabinoid in the brain—altered how mice respond to stress. Administering 2-AG to the animals appeared to make them better able to cope to stressful stimuli, for example. When the researchers gave the animals THC, they found they displayed similar stress resilience, suggesting that THC operates on a similar mechanism as 2-AG.

Patel cautioned against extrapolating the findings in mice to support the use of cannabis for the prevention or treatment of posttraumatic stress disorder (PTSD). As the NASEM report noted, the overall evidence base to support marijuana use for this disorder remains limited, and there are known risks in smoking marijuana. However, he noted that his findings demonstrate how molecules and receptors are important in the stress response, giving other researchers and pharmaceutical companies distinct targets to pursue.

“Although a single report could not hope to address all the complexities of cannabis, cannabinoids, and their health effects, NASEM is to be commended for tackling a massive and often contradictory literature and for making a strong case for the need for further research,” Volkow wrote. ■

“The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research” can be accessed here. Volkow’s blog is available here. Patel’s research paper, “Endocannabinoid Signalling Modulates Susceptibility to Traumatic Stress Exposure” is located here.