The Effect of Cannabinoids (Marijuana) on Neurodegenerative Diseases

Neurodegenerative diseases are one of the most prevalent diseases in the industrialized world, especially among the older generations. There are many treatments that have been developed over the years, including medications, therapies, etc., that have sought to treat the symptoms of these neurodegenerative diseases and mitigate their effects on the patients. Yet, most of these past treatments have had low success rates. However, with the recent discovery of cannabis, many researchers believe that cannabidiol is now the best drug to treat these diseases. Cannabinoids are especially promising due to their anti-inflammatory and antioxidative properties. By studying CBD and other variants, researchers and doctors may finally find a cure for neurodegenerative diseases, or at minimum, a treatment that lessens the impact of the symptoms commonly associated with these diseases. With more research, many pharmaceutical companies will be pressured to pursue the creation of cannabidiol-related drugs and popularize their usage. 

What are Cannabinoids?

Cannabis, specifically cannabidiol, is rich in antioxidative and anti-inflammatory properties, bringing many benefits to its users. Initially, CBD was thought to be a unique substance from marijuana. But in 1960, Mechoulam et al eventually discovered that CBD is the chemical that is found in medical marijuana. [4] For context, medical marijuana is a substance that is used to treat a variety of diseases, including epilepsy, cancer, and chronic pain. THC, on the other hand, is the main ingredient found in recreational marijuana, and is responsible for the psychosis effect that is achieved during a high. Many cannabidiols still have THC present and still use it in their prescriptions when doing experiments with patients.  This means that smaller dosages cause fewer psychosis-like symptoms in patients taking cannabinoids. CBD is the main non-psychotropic molecule that is found in cannabis sativa, although researchers have not yet identified its main function with endocannabinoids (CB1 and CB2 receptors), as it is not clear whether they bind to one, both or neither of the receptors [12]. In total, there are over 550 chemical compounds and phytocannabinoids, which include both CBD and THC, that make up C. sativa.

 As seen in Figure 1, there are specific functions of the CB1 and CB2 receptors that are impacted by the configuration of cannabidiol and that are also responsible for pain levels in patients with these neurodegenerative diseases. 

Figure 1: The chemical makeup of cannabidiol, (CBD) and some of the different functions that it promotes and doesn’t promote. 

Cannabinoids' Effect on Patients With Alzheimer’s 

One of the diseases that CBD may be employed to treat is Alzheimer’s, due to the positive results received from the various clinical and preclinical studies. In the study conducted by Herrmann et al, researchers focused on various symptoms that are very prevalent in Alzheimer patients. According to the group, agitation, which was the main focus of the research, affects 20%-50% of all Alzheimer patients. Agitation is also linked to higher mortality rates, and increased caregiver burden. This study was a random controlled trial, (RCT), and is also classified as Class 1. Researchers used nabilone, a man-made form of cannabidiol, to test thirty-nine patients, whose mean age was 87. This study was done over the course of fourteen weeks. 

For six weeks these patients were given 1-2 mg of nabilone or a placebo, followed by a single-blind placebo for a week after each treatment phase. 

Figure 2: The results of the treatment over the course of the six week trial. (The line in the boxes represents the median and the dots on the line represent the mean of the results.)

The results of the study show that nabilone was clearly favored over the placebo.

Figure 2 shows the clear decrease in the CMAI total score of those exposed to nabilone, compared to those that received the placebo. The researchers also note that while patients received the dosages for the treatment of AD, some experienced sedation, which was remedied by adjusting the dose or by adding drugs to help with the side effect. As seen in Figure 3, there are specific benefits of CBD, such as the reduction of inflammation in the endocannabinoid system.

Figure 3: The main molecular targets of cannabinoids within the brain on Alzheimer’s, including the endocannabinoid system.

Cannabinoids' Effect on Patients with Parkinson’s 

Another prevalent neurodegenerative disease in the industrialized world is Parkinson’s disease, affecting nearly 1 million people in the U.S. and around 8.5 million people worldwide. Parkinson’s disease is known for its connection with dyskinesia, the involuntary tremors and jerks that patients exhibit in various parts of their body, and the large number of people that it affects. A literature review conducted by Lim et al studied three studies that looked into Parkinson’s disease. All three studies were RCTs, and all had 49 patients each. These studies all tested the degree to which levodopa-induced dyskinesia was lessened in these patients exposed to nabilone. The authors also discussed another study that gave 21 patients either a placebo or cannabidiol (75 mg/day or 300 mg/day) for 6 weeks. From an analysis of the data, the results show no clear difference in their UPDRS score, but patients reported a significant bettering of daily lives and functions if they were in the 300 mg/day group. 

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Christine Anyanwu is a current junior from Iowa with a passion for clinical and cognitive neuroscience. In her free time, she loves to watch different medical drama, including Grey's Anatomy, and baking different pastries with her siblings.

References

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