The medicinal use of cannabis dates back as early as 2737 BC, however, these applications have been lost in many parts of the world for the better part of a century. This is due to the fact that the use of cannabis was outlawed in the early 1900s, making scientific research difficult.
In recent years, as cannabis has been decriminalised and legalised in many countries, research into its potential medical applications has rapidly taken place. The cannabis plant has 85 known compounds, referred to as phytocannabinoids or cannabinoids that interact with the human body’s endocannabinoid system (a network of receptors that interact with both naturally occurring cannabinoids in the body in order to regulate a variety of bodily functions). Of the 85 cannabinoids within the cannabis plant, Tetrahydrocannabinol (THC) and Cannabidiol (CBD) are the most prominent. Learn more about how cannabis works when treating disease here.
Cannabidiol (CBD) has largely been the preferred cannabinoid of choice when it comes to research and clinical trials due to the fact that it doesn’t have psychoactive properties and doesn’t elicit euphoria (a ‘high’) when consumed, something that governing bodies like the Food and Drug Administration (FDA) consider an adverse side effect. However, research into Tetrahydrocannabinol (THC) has revealed that it has many of its own unique medical health benefits. These include:
1. Pain relief
It is estimated that one in five, or approximately 1.5 billion people suffer from pain and 1 in 10 are newly diagnosed with chronic pain annually1. Neuropathic, or nerve pain is the most intense of all chronic pain conditions.
There is a great deal of scientific evidence including clinical trials with placebo controls (these are the higher quality types of studies) that demonstrate the efficacy and safety of treating chronic pain, particularly that of a neuropathic nature, with cannabis.
Studies show that THC has moderate pain relieving (analgesic) properties2,3. It works by activating pathways in the body’s central nervous system (CNS) that block pain signals, preventing them from reaching the brain and thus relieving pain.
Interestingly, when it comes to treating pain with THC, low doses have been found to be most effective. This is the case even for those whom conventional pain medications are not effective2. At these doses, researchers do not anticipate THC having a significant impact on the user’s daily functioning.
2. Reducing inflammation
Inflammation is the body’s natural, physiological response to injury and aids in healing. However, in some cases, inflammation may occur due to unresolved infections, abnormal immune responses to normal tissue or other health conditions, including obesity. If these conditions persist, inflammation may become chronic, and lead to DNA damage over time. This can, in turn, lead to the development of cancer.
Chronic inflammation is also thought to play a role in the development of many diseases from arthritis to ulcerative colitis and Crohn’s disease.
Medical evidence suggests that THC can, in certain instances, reduce the production of the immune compounds cytokine and chemokine, which trigger inflammation in the body4.
There is also some pre-clinical evidence that suggests that THC may be able to suppress the genes responsible for the inflammatory response, and thereby reduce inflammation5.
3. Protecting nerve and brain cells
It was once believed that cannabis killed brain cells, however scientific research has revealed that THC has neuroprotective properties, protecting nerve and brain cells thanks to its antioxidative and anti-inflammatory actions as well as its ability to suppress the damage of nerve cells by inhibiting glutamate (a substance which can cause overactivation of the cell receptors which leads to damage)6.
One study which reviewed 446 cases of traumatic brain injury revealed that those who sustained traumatic brain injury but had THC present in their systems had a 2.4% mortality rate, versus those who didn’t, and had an 11.5% mortality rate. After taking all contributing factors into account, the researchers concluded that there was a definite link between THC and the lower death rate in those with these types of traumatic injuries7.
While the full mechanism as to why is not yet understood, it is believed that THC may encourage blood flow to the brain, which brings with it much needed oxygen and nutrients to preserve the endangered nerve cells. Due to the fact that THC also inhibits the overactivation of neurons by glutamate, this may help to prevent the toxic effects that occur after brain injury.
Due to its neuroprotective properties, THC continues to be researched and is showing promise in improving the symptoms associated with various neurodegenerative illnesses including multiple sclerosis, Alzheimer’s disease, Amyotrophic lateral sclerosis (ALS), Huntington’s and Parkinson’s disease.
4. Relaxing muscles
THC has proven muscle-relaxant properties, making it particularly useful to those suffering from health conditions like multiple sclerosis that cause muscle pain, cramping and spasticity8. In fact, THC is one of the ingredients in the only approved drug for the treatment of these conditions.
5. Treating nausea and vomiting
THC’s antiemetic (anti-nausea and vomiting) properties have been studied since the 1970s. In the 1980s, the US Food and Drug Administration (FDA) approved its use by oncologists to treat nausea and vomiting associated with chemotherapy in cancer patients9.
While doctors tend to prescribe traditional medications for anti-nausea therapies, many of these do not alleviate the nausea and vomiting in chemotherapy patients. In these instances, two synthetic cannabinoids which are slightly different variants of THC are prescribed. These medications are Dronabinol (marketed as Marinol) and Nabilone.
Natural cannabis strains containing THC can be used to ease all types of nausea, not just those induced by chemotherapy. THC relieves nausea and vomiting by binding with the receptors of the endocannaboid system in the brain and gastrointestinal tract that control nausea and vomiting as well as intestinal motility (movement of the intestines and their contents)10.
The therapeutic results are dose dependant, and it is found that lower doses are most effective as antiemetics. Higher doses, on the other hand, may have the exact opposite effect, inducing nausea and vomiting instead.
6. Improving appetite
Many chronic health conditions and diseases cause loss of appetite in sufferers. This is particularly true of those with cancer, HIV, hepatitis, dementia and anorexia. Loss of appetite has far-reaching effects on health causing nutritional deficits and over the long term malnourishment which leads to a further compromised immune system, wasting of the muscles and in severe cases, death.
THC has appetite stimulating properties11. Research shows that THC partially binds with CB1 receptors in various areas of the brain and body responsible for appetite as follows:
- Hypothalamus: This is an area of the brain responsible for, amongst various other functions, hunger. When THC binds to CB1 receptors in this region, the hypothalamus releases the hunger-stimulating hormone, ghrelin.
- Basal ganglia: THC acts on this area of the brain and enhances the pleasure of eating.
- Limbic forebrain: It is believed that THC’s influence on this area of the brain increases the palatability of food, making it taste better.
- Stomach and intestines: THC binds with receptors that regulate the hunger hormone ghrelin which not only stimulates appetite but also speeds digestion.
When CB1 receptors are stimulated in these areas, appetite is increased because:
- The hormone peptide tyrosine tyrosine (PYY) which is responsible for signalling the body that it is full12 and to stop eating declines, thus, ghrelin levels rise, stimulating hunger.
- The mTOR (mammalian target of rapamycin) pathway which regulates cellular growth, proliferation, metabolism and food intake is activated, again stimulating ghrelin.
Proopiomelanocortin neurons (POMCs) are activated. These neurons (nerve cells) can either suppress hunger through the primary pathway or suppress it through the secondary pathway. Thus, depending on the strain and dosage, cannabis can be used to either stimulate or suppress appetite.
7. Banning bacteria
THC has antibacterial properties12. The cannabis plant produces THC to protect itself not only from predators but pathogens (disease-causing agents) too. This not only makes it useful in wound healing, but one study found that it may even be useful in treating antibiotic-resistant pathogens like Methicillin-resistant Staphylococcus aureus (MRSA)12 – the bacteria that causes severe wounds and can lead to a life-threatening flesh-eating disease - when other drugs fail.
With antibiotic-resistance on the rise, Cannabis may be the answer in next generation treatment.
8. Easing breathing
Cannabis is a bronchodilator, this means that is opens up the airways, allowing for better oxygen flow and improved breathing, benefits that may be useful in the treatment of breathing disorders like asthma and chronic obstructive pulmonary disease (COPD)13.
9. Combatting cancer
While the value of cannabinoids in the palliative treatment of cancer is accepted due to their antiemetic and anti-nausea properties, there is an increasing body of evidence that demonstrates THC’s anticancer properties.
When it comes to cancerous tumours has been found that cannabinoids6:
- Inhibit the proliferation (reproduction) of cancer cells
- Stimulate the destruction and death of cancerous cells
- Have the potential to prevent tumours from forming new blood vessels to support their growth
- Can ultimately assist in stopping cancer from spreading
Studies show that when combined with certain anti-cancer pharmaceutical drugs, THC can be effective in inhibiting tumour growth. This has been demonstrated in a study on a rare and deadly type of malignant brain tumour known as Glioblastoma multiforme, wherein those who received a mixture of TMZ (a chemotherapy drug) and a 27 mg/ml THC and 25 mg/ml CBD combination, had an 83% 1 year survival rate as opposed to the 44% survival rate in those only receive THC. Due to the results, the study has unexpectedly been continued into its second year14.
Similar tumour-inhibiting properties have been demonstrated in pancreatic adenocarcinoma (pancreatic cancer)6.
10. Curbing addiction
While it may sound ironic as many worry about the potentially addictive properties of cannabis,
scientific evidence shows that it is useful in treating withdrawal symptoms and preventing relapse in those with an addiction to opioids15.
Not only does it allow opioid users to slowly wean off these medications with fewer side effects and is better tolerated than many of the pharmaceutical drugs designed for the same purpose, it also helps to relieve the chronic pain that often leads to opioid addiction in the first place.
The benefits of THC are also being investigated in the treatment of a number of other diseases, and as research advances and more clinical trials are permitted, we’re sure to see many more being added to this list.
- Goldberg D, McGee S. Pain as a global public health priority. BMC Public Health. 2011;11(1). doi:10.1186/1471-2458-11-770
- Wilsey B, Marcotte T, Deutsch R, Gouaux B, Sakai S, Donaghe H. Low-Dose Vaporized Cannabis Significantly Improves Neuropathic Pain. The Journal of Pain. 2013;14(2):136-148. doi:10.1016/j.jpain.2012.10.009
- McQuay H. More evidence cannabis can help in neuropathic pain. Can Med Assoc J. 2010;182(14):1494-1495. doi:10.1503/cmaj.100799
- Nagarkatti P, Pandey R, Rieder S, Hegde V, Nagarkatti M. Cannabinoids as novel anti-inflammatory drugs. Future Med Chem. 2009;1(7):1333-1349. doi:10.4155/fmc.09.93
- Yang X, Hegde V, Rao R, Zhang J, Nagarkatti P, Nagarkatti M. Histone Modifications Are Associated with Δ9-Tetrahydrocannabinol-mediated Alterations in Antigen-specific T Cell Responses. Journal of Biological Chemistry. 2014;289(27):18707-18718. doi:10.1074/jbc.m113.545210
- Śledziński P, Zeyland J, Słomski R, Nowak A. The current state and future perspectives of cannabinoids in cancer biology. Cancer Med. 2018;7(3):765-775. doi:10.1002/cam4.1312
- Nguyen B, Kim D, Bricker S et al. Effect of Marijuana Use on Outcomes in Traumatic Brain Injury. Pdfs.semanticscholar.org. https://pdfs.semanticscholar.org/63b4/0ed62b768538f34c7fc7c8030b7b7e1ff460.pdf. Accessed January 15, 2019.
- Mack A, Joy J. MARIJUANA AND MUSCLE SPASTICITY. Ncbi.nlm.nih.gov. https://www.ncbi.nlm.nih.gov/books/NBK224382/Published 2000. Accessed January 15, 2019.
- Gunby P. Many cancer patients receiving THC as antiemetic. JAMA: The Journal of the American Medical Association. 1981;245(15):1515. doi:10.1001/jama.1981.03310400007003
- Sharkey K, Darmani N, Parker L. Regulation of nausea and vomiting by cannabinoids and the endocannabinoid system. Eur J Pharmacol. 2014;722:134-146. doi:10.1016/j.ejphar.2013.09.068.
- Davis J, Choi P, Kunze J, Wahl P. Society for the Study of Ingestive Behavior. Ssib.org. http://www.ssib.org/web/press2018.php. Published 2019. Accessed January 15, 2019. Wynne, K. and Bloom, S. (2006). The role of oxyntomodulin and peptide tyrosine–tyrosine (PYY) in appetite control. Nature Clinical Practice Endocrinology & Metabolism, 2(11), pp.612-620.
- Appendino G, Gibbons S, Giana A et al. Antibacterial Cannabinoids fromCannabis sativa: A Structure−Activity Study. J Nat Prod. 2008;71(8):1427-1430. doi:10.1021/np8002673
- Effect of Cannabis on Airflow Obstruction. Medscape.org. https://www.medscape.org/viewarticle/747982_3. Published 2019. Accessed January 15, 2019.
- Dumitru C, Sandalcioglu I, Karsak M. Cannabinoids in Glioblastoma Therapy: New Applications for Old Drugs. Front Mol Neurosci. 2018;11. doi:10.3389/fnmol.2018.00159
- Wiese B, Wilson-Poe A. Emerging Evidence for Cannabis' Role in Opioid Use Disorder. Cannabis Cannabinoid Res. 2018;3(1):179-189. doi:10.1089/can.2018.0022