Scientific Community Continues Searching for Answers to Cannabinoid Questions


State and local marijuana laws continue to evolve toward legalization much faster than the scientific community can collect the data to help society weigh the health, safety, and ethical ramifications of these new laws.

SAN DIEGO — State and local marijuana laws continue to evolve toward legalization much faster than the scientific community can collect the data to help society weigh the health, safety, and ethical ramifications of these new laws.

Meanwhile, across the United States, patients looking for relief from everything from glaucoma to migraines want to know if it can be found in an oil or edible at the new local dispensary, but the medical community cannot give them a definitive answer.

Unfortunately, none of that is expected to change anytime soon, according to science and policy experts who spoke Monday at the American College of Rheumatology (ACR)/Association of Rheumatology Health Professionals 2017 Annual Meeting during a discussion titled: Cannabis in Society and Medical Practice.

It took decades for the scientific community to learn all that it knows about the health effects of tobacco and alcohol. It’s going to take just as long to collect the robust data that will allow researchers to determine the long-term health effects of cannabis, said Rosalie Pacula, PhD, who is a senior economist and co-director of the Rand Drug Policy Research Center. The patchwork of state laws on the sale, possession and prescription of cannabis in the US, coupled with federal restrictions that block researchers’ access to it for study, are slowing the process and making a lot of the available data suspect, according to Pacula and Daniele Piomelli, PhD, director of the Institute for the Study of Cannabis at University of California Irvine.

“Policy doesn’t wait for scientific research,” Pacula said. Given the sizable tax revenue to be made from cannabis sales, this is unlikely to change, she said. For example, Colorado reported $193.6 million in cannabis tax revenue in 2016 and Washington reported $189.2 million, she said.

One major deterrent to collecting sound data for studying cannabis is the heterogenicity that exists between the jurisdictions where it is legalized, she said. A medical marijuana law in one state could be much more restrictive than a medical marijuana law in another state. A medical marijuana state isn’t the same as a state where cannabis can be purchased at a retail dispensary.

While there may be early data in some states to answer seemingly simple questions, such as whether there’s an increase in the adult use of cannabis in states with marijuana legalization, it may still too early to determine whether that is a good thing or bad thing, Pacula said.

In what form are people using cannabis? How strong is the concentration of the cannabinoid in the product? Where is the consumer buying it? Answers to all of these questions could skew the scientific data, Pacula said.

For instance, a study by the National Institutes of Health may use cannabis with 5% THC, the cannabinoid responsible for its psychoactive effects. Meanwhile, cannabis sold in a dispensary in flower form is generally 20% and in oil form it could be as much as 70%, she said.

While scientists and policy makers may find sound data lacking, the cannabis industry is not necessarily deterred from using available statistics to market their products, Pacula and Piomelli said.

Meanwhile, health care providers need information about what indications cannabis has been proven to benefit. What is the proper dosing for different indications, which is a question they can answer for FDA-approved drugs? Can cannabis be used to replace opioids or complement them? And where can clinicians obtain their education on cannabis?

All are very important questions that need to be addressed, Piomelli explained.

“We need more medical education for medical practitioners, nurses, dispensing staff,” he said, recalling a study that found 90% of marijuana dispensary staff admitted to dispensing advice in addition to cannabis, although only 10 percent had any relevant education.

“What the cannabis industry is telling you is not based on data: It could be right, but it’s not based on data,” he said.

In January 2017, the National Academy of Sciences released a voluminous report on the Health Effects of Cannabis and Cannabinoids, which is publicly available and reaches more than 100 conclusions. The findings, based on the review of 10,000 published studies, contradict many widely-held assumptions about cannabis, said Piomelli, who was a member of the committee that produced the report. For instance, the report found insufficient evidence that cannabis has a positive effect on glaucoma, Huntington’s Disease and Parkinson’s disease.

However, the report concludes there is sufficient data to show cannabis has an effect for indications such as chronic neurological pain and multiple sclerosis, he said. The committee that produced the report recommends expanded cannabis research and enhanced data collection.

While state laws are evolving, federally cannabis has been listed as a Schedule I drug under the Controlled Substances Act, the most tightly restricted category reserved for drugs since 1972.

“It’s important for the federal government to change the scheduling (of marijuana) so that scientists can access it for study. Right now, all they’re doing is impeding research,” he said.


Sigal LH. 4M122ARHP: Cannabis in Society and Medical Practice. Presented at: 2017 ACR/ARHP Annual Meeting; November 3-8, 2017; San Diego.

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