Everything you need to know about THC

In Feature Stories, Research Topics by Katrina Eschner

Tetrahydrocannabidiol, or THC, is both the primary psychoactive component in cannabis and the “cannabinoid”—or medically active ingredient—that has historically made up the largest percentage of such compounds in most marijuana strains. As debates about the value of marijuana as medicine in North America have unfolded over the past decade and a half, we’ve all heard THC mentioned.

Medical marijuana scientists today concede that high-THC marijuana is not always the best medicine, while new light has been shed on the value of other cannabinoids present in THC. Cannabinoids such as cannabidiol (CBD) are proving to have powerful therapeutic uses, meaning that the chemical constitution of marijuana is being transformed, via cultivation, for the medical setting.

But THC remains at the centre of the medical marijuana story; its history, and its well-known effects, continue to power the medical marijuana conversation occurring across the globe as well as our cultural understanding of what marijuana is and what it can do.

What is THC?

THC is one of a host of chemicals called cannabinoids within the marijuana plant that have the power to affect how we feel pain, how we perceive our surroundings, and how our bodies cope with inflammation. In the human brain, THC works by binding with cannabinoid receptors on the brain’s neurons. These receptors affect how neurotransmitters—chemicals whose job is to transmit signals from neuron to neuron—send information.

In 2003, science journal Nature published a story detailing the “enormous” clinical potential of medical marijuana. “The endocannabinoid system has an important role in nearly every paradigm of pain, in memory, in neurodegeneration and in inflammation,” the journal stated.

Cannabinoid receptors weren’t created solely for marijuana; phytocannabinoids, or plant-produced cannabinoids, are just one of three kinds of chemicals that interact with this bodily system. Anandamide is foremost among the endocannabinoids, or chemicals produced within the body that interact with cannabinoid receptors. Named after the Sanskrit word for “bliss” and sometimes referred to as the “bliss molecule,” it’s been connected to substances such as chocolate. Endocannabinoid activity has also been proposed as one possible explanation for the “runner’s high” experienced by athletes.  Synthetic cannabinoids are the third type, and they are known to be manufactured chemically.

Modern scientific evidence stretching back to the 1960s suggests that THC and other plant-produced cannabinoids have significant therapeutic potential. This wouldn’t be news to historical cultures across Central and South Asia, many of which used marijuana to address a host of medical needs as well as for its psychoactive properties which at times played a recreational and spiritual role in their lives.

The body’s endocannabinoid system has two kinds of receptors, and THC only interacts with one of them. As this New York Times article discusses, THC stimulates CB1 receptors in the central nervous system—your brain and spinal cord—and is responsible for the trademark symptoms exhibited by Cheech & Chong. For those benefitting from other aspects of medical marijuana’s power to heal, these symptoms fall under the category of “undesirable side effect” rather than medical treatment.

However, for cancer patients suffering from chemotherapy-related nausea, or AIDS sufferers experiencing the “wasting” associated with their illness, some symptoms of being high, such as “the munchies,” can play an important therapeutic role.

How does THC compare with other cannabinoids?

Other cannabinoids, such as CBD, have come under medical scrutiny for their ability to stimulate CB2 receptors in the immune system and the peripheral nervous system (the nerves throughout your body). In some cases, their pain-relieving and anti-inflammatory effects have been combined with THC, as in new drugs developed by pharmaceutical companies.

In many other instances, however, researchers have sought to produce minimal-THC drugs from cannabis. One example of this phenomenon is “Charlotte’s Web,” a high-CBD strain of marijuana named after young Dravet Syndrome sufferer Charlotte Figi. The child’s numerous debilitating seizures drove her parents to dose their daughter with an exceptionally low-THC strain of marijuana, administered as an oil. They quickly saw beneficial results.

Since the Figi family story went national last summer with the release of CNN’s documentary Weed, Colorado has become home to numerous other so-called “marijuana refugees” seeking legal treatment for their own epileptic children. But Charlotte’s physician, Dr. Alan Shackelford, was recently quoted as saying that doctors aren’t certain exactly why Charlotte’s Web, a marijuana strain initially named “Hippie’s Disappointment” for its low THC content, has such a dramatic effect on child epilepsy sufferers.

“The cannabidiol seems to act as a neuro stabilizer, but how? The research is miniscule on this,” he said in a local newspaper article.

Dr. Shackelford’s comments speak to the difficult and slow path modern marijuana research has taken. For the Western world, appreciating marijuana’s medical potential has been a long journey. A major step on that journey was taken in 1964.

THC history

In the mid-twentieth century, when Dr. Raphael Mechoulam first became interested in the chemical makeup of cannabis, “research with it was a laboratory nightmare,” he told the journal of the Society for the Study of Addiction. “From a scientific point of view cannabis research had effectively been eliminated.”

Working at Israel’s Weizmann Institute of Science, he was the first person to isolate, analyze and synthesize THC. For his research, published in 1964, he used marijuana confiscated by the police.

In the half-century since that first paper, Mechoulam, now 82, has remained a leading light in the field of cannabinoid study. His research, which later included expanding previous researchers’ work into CBD and isolating the endocannabinoid anandamide, has shaped scientific understanding of the medical properties of the cannabis plant.

It may be no accident that the world’s leading medical marijuana scientist comes from Israel, a country with a strong track record of supporting medical marijuana efforts. Currently, medical marijuana is legal and highly regulated in Israel, and the country is home to efforts in cultivating new strains of marijuana with a higher proportion of medically active ingredients.

Where does THC go from here?

Although THC is perhaps the best-known substance in marijuana, it’s fast becoming merely one tool in the medical marijuana arsenal. Current medical cannabis science has focused on deleting the cannabinoid’s recreational effects in favour of holding on to its medical ones or bringing out the positive effects of other substances, such as CBD, to create medically effective treatments.

As The Medical Marijuana Review recently reported, Canadian medical marijuana company MediJean is currently working with 224 different strains of marijuana to create ailment-specific medicines. In Israel, work is being done on developing new ways of offering the medicine to patients. The medical potential of THC has not yet been fully explored, and, as with all marijuana-related substances, further study is needed. But in a changing context, there is hope that the necessary study will take place.

Photo courtesy Flickr user  medcannaman

KatHeadshotABOUT THE AUTHOR

Kat Eschner is a Toronto-based freelance writer who’s covered topics from palliative care to the Olympics. Find her on Twitter @KatEschner or at Kateschner.com.