Does Medical Marijuana Help Improve Parkinson's Symptoms?

Medical marijuana, known also as medical cannabis, has had mixed clinical results as a treatment to alleviate symptoms of Parkinson’s disease (PD). The effects of marijuana on the symptoms of Parkinson’s are not definitive. Some people report improvement in ease of movement and reduction of pain, while others report no change, or even feeling worse.

Cannabis has lots of nicknames including marijuana, pot, weed, dope, grass, and ganga.

Where is marijuana use legal?

As of November 2017, marijuana use is legal for medical use in 29 states, and 5 states (CT, IL, MA, NM, NY) have approved it specifically for PD. Use should be physician certified, and then patients must register to possess and use any form of marijuana.

Tetrahydrocannabinol (THC) is the primary psychotropic cannabinoid in marijuana. It can cause alterations in perception, mood, and behavior. Its effects last for a long time. This creates measurement challenges when establishing or evaluating therapeutic doses.2

How cannabinoids work

Cannabinoids occur naturally in humans, plants, and chemicals. Our bodies make endocannabinoids, which bind to receptors found throughout the body and brain. This is called the endocannabinoid system. Cannabinoids can bind to receptors that affect brain chemicals, including dopamine. Low dopamine levels characterize Parkinson’s. The basal ganglia area of the brain controls motor function and also contains cannabinoid receptors. The cannabinoids in marijuana work in some of the same ways as those made by the body.3 Cannabinoids in marijuana may have antioxidant and anti-inflammatory effects that could be neuroprotective.2

Mixed research results

There are some inherent flaws in the study design of research that evaluates the effects of medical marijuana. Most studies report on effectiveness through self-reporting; they are observational. Whether by telephone interviews or completing questionnaires, there is a subjective component to the reporting. Similarly, there is no universal deliverable source of marijuana. Unlike pills or IV therapy, there is no reliable measure or consistent potency of cannabis.3

Marijuana varies by cannabis strain, from plant to plant and the cultivated level of THC in any one variety. This means that individuals who get their own pot have no way to determine the level of THC they are exposed to. Marijuana is generally smoked in cigarette form, but there are other formulations like edible and topical cannabinoids.2

What are the benefits?

Marijuana improved both motor and non-motor symptoms of Parkinson’s in several studies.

Relief was reported in pain reduction, improved sleep, and some psychological components.4 No major adverse effects were reported.

Other clinical trials reported no change in motor skills, but some reported fluctuations in drug-induced involuntary muscle movement.

What are the risks?

Potential benefits of marijuana use need to be compared to possible side effects both on an aggregate level in large scale studies as well as evaluated on an individual basis. A small percentage of people experienced nausea and dizziness, hallucinatory episodes, and some alteration of executive function.2 We don’t yet know enough about drug interactions with marijuana use.

More research is needed

The safety, tolerability, and side effects of medical marijuana require further study. Meaningful benefits have not been substantiated across study populations. As researchers gain a more complete understanding of how the endocannabinoid system works, results may yield more information on the efficacy (the ability to produce desired results) of using marijuana to ease the symptoms of Parkinson’s disease.

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