Research Round Up: Medical Marijuana and Parkinson’s Disease at a Glance

With medical marijuana legalized in 28 states and Washington, D.C., its therapeutic properties have become buzzworthy. Researchers are currently studying these properties and how they affect different diseases, like Parkinson’s disease (PD). But why?

Introduction to Marijuana

Marijuana’s plant name is cannabis. When administered, it effects the endocannabinoid system, which is in the brain and made up of cannabinoid receptors that link to brain cells that regulate thinking and some body functions.

Cannabis contains more than 100 neuroactive chemicals that work with two types of cannabinoid receptors that are located in the brain. Cannabinoids (a chemical compound found in cannabis) have powerful, indirect effects on these receptors, but researchers are unsure how.

Cannabis can contain molecules that interact with cannabinoid receptors and behave like an agonist, a drug that attaches to the same receptor as a natural chemical and stimulates or tickles it. An antagonist is different, it attaches to the receptor, but blocks the action of the natural chemical. Medical marijuana can contain both cannabinoid agonists and antagonists. The amounts of each vary with different types of marijuana plants and strains. Because of these unknown amounts in addition to the multiple ways marijuana can be administered and the difficulty in measuring dosages, medical marijuana studies are difficult to conduct.  Read an in-depth description of the science behind marijuana here.

A primary component of marijuana is delta-9-tetrahydrocannibinol (THC), a type of cannabinoid. Cannabidiol is the other primary component.

Marijuana and Parkinson’s

In part, due to the popularity of people with Parkinson’s posting videos showing how marijuana helps with tremors and dyskinesia, there has been a new enthusiasm from the research community to study medical marijuana’s effect on PD. However, despite several clinical studies, it has not yet been proven that cannabis can directly benefit Parkinson’s symptoms though most experts believe there will be positive effects in some patients. Studies will hopefully guide us to use the marijuana for specific patients and specific symptoms.

The use of cannabinoids has been suggested to help with managing neurological and non-neurological conditions. Literature on medicinal marijuana is incredibly varied. Researchers issue caution for people with PD who use cannabis because of its effect on thinking. Because Parkinson’s can impair the brain’s executive function (the ability to make plans and limit risky behavior), people with PD should be cautious about using any medication that can compound this function.

Some researchers think that cannabidiol might be neuroprotective — saving neurons from damage caused by Parkinson’s. Cannabinoids (the drug molecules in marijuana) have also been studied for use in treating other symptoms, like bradykinesia and dyskinesia (excess movement caused by levodopa). Despite some promising preclinical findings, to date researchers have not developed solid evidence of the cannabis benefits for people with Parkinson’s.

While some results have been positive, the effects of medical marijuana are not completely understood, which is why more studies, especially those that enroll a greater number of subjects, are needed. Medical marijuana studies primarily provide participants with THC and/or cannabidiol in the form of a capsule, nasal spray or liquid.

Medical Marijuana by the States

  • Parkinson’s is a qualifying condition for medical marijuana in: Arizona, Connecticut, Florida, Illinois, Maine, New Mexico and New York, Pennsylvania and Rhode Island.
  • States that legalized medical marijuana: Alaska*, Arizona, Arkansas, California*, Colorado*, Connecticut, Delaware, Florida, Hawaii, Illinois, Maine*, Maryland, Massachusetts*, Michigan, Minnesota, Montana, Nevada*, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oregon*, Pennsylvania, Rhode Island, Vermont, Washington*, Washington, D.C.*
  • Minnesota, New York and Ohio do not allow medical marijuana to be smoked.
  • Only people with epilepsy qualify for medical marijuana in Texas.
  • States can either require patients register to possess and use medical marijuana or require a document written by a physician confirming the patient has an approved condition.

*denotes marijuana legalized recreationally.

Is Medical Marijuana an Option for Me?

A survey conducted across 40 Parkinson’s Foundation Centers of Excellence asking PD physicians about their opinion on cannabis shows that the Parkinson’s community is not afraid to ask their doctor about marijuana. Ninety-five percent of neurologists have been asked to prescribe medical marijuana. Because it’s benefits have not been proven through clinical trials, physicians are hesitant to support cannabis for PD symptoms. They would be more willing to sign off on medical marijuana if it were approved by the Food and Drug Administration.

There are risks and benefits associated with the use of cannabis for people with PD. Benefits can include a possible improvement in: pain management, sleep dysfunction, weight loss and nausea. Potential adverse effects can include: impaired cognition, dizziness, blurring of vision, mood and behavioral changes, loss of balance and hallucinations. Chronic use can increase risk of mood disorders and lung cancer.

Is medical marijuana an option for me? “Marijuana should never be thought of as a replacement for dopaminergic and other approved therapies for Parkinson’s disease,” said Dr. Michael S. Okun, Parkinson’s Foundation National Medical Director. The bottom line is that research still needs to determine how medical marijuana should be administered and how its long-term usage can impact Parkinson’s symptoms.

Your first step should be to talk to your doctor about medical marijuana. “We have an open mind on the use of marijuana in Parkinson’s, but be careful if you and your doctor decide it is right for you and remember not to drive under the influence (people under the influence or marijuana who drive are at twice the risk of a car accident),” said Dr. Okun. Finally, remember that smoking may be harmful to the lungs and that edibles can be more powerful than some patients expect.

To learn more about medical marijuana and Parkinson’s read our in-depth article.


Dr. Joseph JankovicJoseph Jankovic, MD, is the Director of the Parkinson’s disease Center and Movement Disorders Clinic Baylor College of Medicine, a Parkinson’s Foundation Center of Excellence. Information from this article is attributed to Dr. Jankovic’s data and presentation at the Foundation’s 2016 Center of Leadership Conference.


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