The Science of Medical Marijuana: What’s the Latest?

Written by R. Sam Barclay

Scientists gathered at the annual meeting of the American Association for the Advancement of Science to talk shop on medical marijuana.

To date, nearly half of the states in the U.S. have legalized medical marijuana.
However, because the drug remains illegal at the federal level, the Food and Drug Administration (FDA) has not regulated it.
This leaves medical users to navigate treatment on their own. The issue was a prime topic at the annual meeting of the American Association for the Advancement of Science this week in San Jose, California.

Humans have used cannabis for thousands of years. But only in the past few decades have scientists begun to understand how the wide range of chemicals found in cannabis work in the body.

“We’re in much better shape now than we ever have been to know exactly what’s in there, so we can have cannabis that’s quantified in terms of the major psychoactive ingredients,” explained Mark Ware, director of clinical research at the Alan Edwards Pain Management Unit at the McGill University Health Centre, in an interview with Healthline.

What, Exactly, Is in Marijuana?

Among these ingredients are at least 104 active cannabinoids. They mimic the actions of signaling chemicals in the brain called endocannabinoids, which dock with specific receptors on the surface of cells. Some cannabinoids also dock with other receptors, including those for serotonin and adrenaline.
The most famous of these chemicals is delta-9-tetrahydrocannabinol (THC), which is largely responsible for cannabis’ intoxicating effects.

Meet the Cannabinoids

• delta-9-tetrahydrocannabinol (THC)
• tetrahydrocannabivarin (THCV)
• cannabigerol (CBG)
• cannabidiol (CBD)
• cannabidiolic acid (CBDA)

Each chemical acts on different receptors in different ways.
For example, THCV blocks the mind-altering effects of THC while simultaneously combatting inflammation in the body, which may help relieve symptoms of Parkinson’s disease and protect against liver damage. It also changes how the serotonin receptor behaves during psychosis, potentially offering a treatment for schizophrenia.

Meanwhile, CBG’s unique profile of activity at adrenaline and serotonin receptors makes it a prime candidate for treating pain.
CBD and CBDA, on the other hand, are better candidates to treat nausea.
Other possible uses of cannabinoids include treating stroke, PTSD, epilepsy, and even drug addiction itself.

Other Compounds Found in Marijuana

Cannabis also contains at least 400 other compounds, such as terpenes, limonenes, and flavonoids. Also found in scented herbs like thyme and oregano, these aromatic compounds are what give the different strains of marijuana their distinctive colors, tastes, and scents.
Ware explained that these compounds may also have anti-inflammatory, anti-seizure, and possibly even pain-killing effects.

Eventually, patients seeking relief may have access to a wide range of FDA-approved medications, each with the right combination of compounds to treat their specific symptom set.
These cocktails could be more effective than the currently FDA-approved, THC-mimicking, dronabinol (Marinol). Marinol has failed to displace medical cannabis despite being available to treat nausea and other conditions since 1985.

Another drug derivative is nabiximols (Sativex), a blend of THC and CBD for multiple sclerosis patients.

For chronic pain management nowadays, it’s rare that I have patients that leave my clinic on one single drug.

Mark Ware, McGill University Health Centre

Drug mixtures should come as no surprise to those experienced with major medical conditions.
“For chronic pain management nowadays, it’s rare that I have patients that leave my clinic on one single drug,” Ware explained.

“They need several different agents that all act on slightly different receptors, and the right combination of those drugs helps alleviate the pain to allow them to improve their functioning and quality of life. I think cannabis is probably the same way — it’s not one ingredient; it’s multiple, each of which works on slightly different receptors. I think the challenge is trying to figure out what is that correct combination of receptor targets.”

Herbal Solutions Are an Option

Such drugs will take decades to develop and reach the market. Until then, patients have herbal cannabis as an option.
However, there are dozens of strains of cannabis on the market, each claiming to have different properties for treating different symptoms.
Cannabis suppliers also often have a hard time controlling the quality of their product, meaning that two batches of the same strain could vary in potency and chemical composition.

We’ve got thousands of patients who’ve been using marijuana now in some kind of legal regime for dozens of years … we could be learning from that interaction between patient and plant to see: Are there some combinations of cannabinoids that are better for certain symptoms than others?

Mark Ware, McGill University Health Centre

Ware proposes studying existing registered medical cannabis users to start generating useful information. His home province of Quebec will soon start such an experiment.

“We’ve got thousands of patients who’ve been using marijuana now in some kind of legal regime for dozens of years, and nobody’s ever tracked these patients over time,” he said. “We have learned nothing in terms of safety or why they’re using it. We could track the patients, we could map the patients’ [symptoms] with the particular cannabis that they’re using, and we could be learning from that interaction between patient and plant to see: Are there some combinations of cannabinoids that are better for certain syndromes and symptoms than others?”

Cannabis, however, isn’t without risk. Certain groups should avoid using the drug, including:

• pregnant women: Cannabis can deform the brain of a developing fetus.
• people with a heart condition: Cannabis temporarily widens the blood vessels, lowers blood pressure, and increases heart rate.
• people with a family history of schizophrenia or psychosis: Cannabis may activate a latent predisposition for mental illness.
• people under the age of 25: Cannabis may interfere with how the brain matures during adolescence and young adulthood.
• people who are driving, especially those who have consumed alcohol: Even small amounts of alcohol and cannabis can amplify one another’s effects, drastically increasing the rate of driving mistakes.

However, beyond these risks, the majority of studies examining the dangers of cannabis have found no long-term effects after a month of nonuse. This includes a study published earlier this year showing that cannabis use does not change the volume or shape of important parts of the brain.
Either way, the question of medical cannabis isn’t whether using the drug is more dangerous than abstinence. The question is whether cannabis can provide more effective symptom relief, with fewer side effects, than existing medications.

“The message here is not that cannabis is useful for everybody, it’s that for those severely affected people it may be an option,” said Ware. “You want a clean, healthy brain that’s wiring up properly. You want a clean, healthy fetus. You want clean, healthy drivers. It’s just common sense.”