Sensationalist headlines concerning the alleged cancer-busting abilities of cannabis have sparked a huge amount of interest in this once maligned plant, with polls suggesting that more people than ever before now support the use of medical cannabis. Accordingly, governments around the world have been busy repealing prohibitionist laws in order to allow for increased access to the drug, which is now commonly used to treat a range of conditions including neuropathic pain and epilepsy.
However, the science behind the medical properties of cannabis is in fact much more complex than many people might think, and the reality is that huge gaps still exist in our knowledge of how the plant works.
More Than Just THC And CBD
By now, most people have heard of the compounds tetrahydrocannabinol (THC) and cannabidiol (CBD), both of which are commonly cited as the source of weed’s medical efficacy. The truth, however, is that cannabis contains more than 500 compounds, all of which are thought to contribute to the plant’s pharmacological properties. Of these, around 100 are classed as phytocannabinoids, which means they bind to the cannabinoid receptors within our central nervous systems.
Both THC and CBD are phytocannabinoids, with the former being largely responsible for the psychoactive effects of cannabis thanks to its binding affinity for the cannabinoid 1 (CB1) receptor, while the latter is often credited with treating inflammation, anxiety, and depression by reacting with the cannabinoid 2 (CB2) receptor. Yet a number of other phytocannabinoids – including cannabigerol (CBG) and cannabichromene (CBC) – are also believed to play a role in shaping the drug’s effects, with new discoveries continually adding to our understanding of these compounds.
Last year, for instance, researchers identified a previously unknown phytocannabinoid called tetrahydrocannabiphorol (THCP), which has a binding affinity for the CB1 receptor that is 33 times that of THC. This discovery cast doubt on everything we thought we knew about weed, leading some to suggest that it may be THCP, rather THC, that gets users high.
On top of all that, the plant is also loaded with terpenes, which are essential oils that not only give each cannabis strain its unique smell and taste but also generate an array of pharmacological and medical effects. Though way more research is needed in order to determine the true value of each of these compounds, it is generally believed that the overall properties of a given strain are shaped by the interactions between its various ingredients rather than by any one particular molecule. The combined action of these compounds is often referred to as the entourage effect.
Cannabis and Cancer
While stories about cannabis curing cancer abound, it’s worth pointing out that no proper clinical trials into the drug’s anti-cancer properties have ever been conducted. However, a great deal of preclinical evidence, mostly involving animals, has indicated that several of the compounds in cannabis may help to treat the condition.
For example, THC has been found to slow the development of colitis-associated colon cancer in mice, predominantly by inhibiting the release of the pro-inflammatory protein interleukin-22. In a separate study, the same cannabinoid-induced apoptosis in breast cancer cells, though a more recent paper concluded that only cannabis strains that are high in CBD are effective at treating certain types of cancer. Conflicting findings such as these have sparked a huge amount of confusion and debate regarding the mechanisms underlying weed’s medical properties while adding weight to the entourage effect theory.
Cannabis and Inflammation
Many of the compounds present in cannabis have been found to be anti-inflammatory, not least THC and CBD. As a consequence, the drug is often used to treat conditions such as fibromyalgia and multiple sclerosis, which are linked to neuroinflammation. In addition, CBG is believed to prevent the release of inflammatory proteins such as interleukin-6 and prostaglandin E, and has consequently been associated with reduced inflammation in the brain.
In animal models, both CBG and CBD have displayed the capacity to attenuate symptoms of Parkinson’s and Huntington’s diseases, primarily by protecting neurons from inflammation. It is generally believed that these anti-inflammatory responses are mediated by the CB2 receptor, and further research has indicated that both CBC and a terpene called beta-caryophyllene are capable of binding to this receptor. As such, both of these lesser-known compounds are now thought to play a role in the neuroprotective effects of cannabis.
The Anti-Bacterial Effects of Cannabis
Both CBD and CBG are believed to have strong anti-microbial properties and have even been touted as a possible solution to the growing problem of antibiotic resistance. The highly resilient bacteria methicillin-resistant Staphylococcus aureus (MRSA), for instance, is prevented from forming into colonies called biofilms when in the presence of CBG, which disrupts the microbe’s cytoplasmic membrane.
In addition, a terpene called pinene – which is also found in pine trees and is responsible for their unmistakable scent – has been shown to disrupt the membrane and the metabolism of a bacteria called Campylobacter jejuni, which is a major cause of food poisoning and is becoming increasingly resistant to antibiotics.
Cannabis and Epilepsy
The use of cannabis to treat epilepsy has received global attention in recent years, and a number of countries have relaxed their cannabis laws specifically in response to the plight of certain children who have seen their seizures decrease after using the drug. However, exactly which compounds in cannabis are required in order to treat the condition remains a hotly-contested issue.
Though initial reports suggested that CBD was predominantly responsible for preventing seizures, more recent research has indicated that the presence of THC is in fact necessary for a cannabis strain to be effective – thereby further bolstering the entourage effect theory.
Further evidence for the entourage effect can be seen in the numerous interactions that exist between THC and certain other cannabis compounds. For instance, it has been demonstrated that the presence of CBD counteracts the memory loss that can be caused by high levels of THC, while a sedative terpene called myrcene enhances the ability of THC to make people feel stoned.
All things considered, there’s clearly a lot going on inside this fascinating plant. However, with so many holes in our understanding of how cannabis works, many doctors remain reluctant to prescribe it to their patients, calling instead for more research into the numerous unanswered questions regarding the drug’s medical benefits.