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Ask the MD: Medical Marijuana and Parkinson’s Disease

When it comes to treating Parkinson’s symptoms, especially with non-traditional approaches, many people are curious if and how medical marijuana might work, and what research supports it.

As of October 2019, the U.S. Food and Drug Administration (FDA) has not approved medical marijuana for any use. But 33 states and the District of Columbia have legalized medical marijuana for certain conditions; in some states, this includes Parkinson’s disease (PD).

Here we answer common questions about medical marijuana and Parkinson’s.

What Is Medical Marijuana?
Medical marijuana is marijuana used to treat disease or ease symptoms of disease.

Marijuana, or cannabis, comes from the plant Cannabis sativa. Marijuana contains approximately 100 different compounds called cannabinoids. The main cannabinoid, tetrahydrocannabinol (THC), causes the “high” — variably described as happiness, amusement or contentment — that comes with marijuana. THC may help nausea, pain or muscle spasms, but it also can affect mood, behavior and thinking. The second most common cannabinoid, cannabidiol (CBD), doesn’t cause mind-altering effects and could potentially have beneficial effects for treating disease.

Marijuana and cannabinoids can be taken several different ways — smoking dried leaves, swallowing pills or spraying liquid under the tongue are a few examples. The amount of THC, CBD and other cannabinoids varies in each different formulation (and plant).

What Is the Research on Cannabinoids and Parkinson’s?
Our bodies make natural cannabinoids that control sleep, appetite, mood and other processes by binding to receptors throughout the body and brain. These receptors are found in particularly high numbers in the basal ganglia, a circuit of brain cells that controls movement and is affected in Parkinson’s. Because the cannabinoids in marijuana bind to the receptors in our body and brain, researchers have looked at whether they could bind to basal ganglia and other receptors to modify the course of PD or help ease symptoms of disease.

Pre-clinical work, including several studies funded by MJFF, shows that cannabinoids may protect brain cells through antioxidant and anti-inflammatory mechanisms.

Clinical studies have evaluated whether marijuana can ease Parkinson’s motor and non-motor symptoms as well as levodopa-induced dyskinesia, involuntary movements that may result with long-term use of levodopa and many years of living with PD. In general, trials show mixed results (some positive, some negative), which leaves patients, doctors and researchers with insufficient evidence that medical marijuana and cannabinoids are an effective treatment for Parkinson’s.

Notable trials on motor symptoms (tremor, slowness, stiffness):

  • A randomized, placebo-controlled, double-blind trial* of two different doses of CBD capsules improved quality of life but not motor symptoms in 21 people with PD.
  • An open-label study** of smoked marijuana decreased tremor and slowness in 22 people with PD.

For non-motor symptoms:

  • An open-label study** of CBD tablets decreased psychosis — hallucinations (seeing things that aren’t there) and delusions (having false, often paranoid, beliefs) — in six people with PD.
  • An open-label study** of CBD tablets lessened symptoms of REM sleep behavior disorder (acting out dreams) in four people with Parkinson’s.

Formal studies on other non-motor symptoms have not been conducted, but many individuals cite anecdotal benefit on pain, anxiety and sleep problems (as well as motor symptoms).

Noteworthy trials on levodopa-induced dyskinesia:

*In a randomized, placebo-controlled, double-blind trial, one group of participants receives the study drug while another receives placebo (an inactive substance that looks exactly like the study drug). Neither participant nor researcher knows who is getting study drug or placebo.
**In an open-label study, there is no placebo group, and both participants and researchers know what treatment is being given.

Why Is Researching Marijuana Difficult?
Several factors limit the ability to perform research on marijuana and interpret results.

Regulations surrounding marijuana research may deter investigators. The federal government classifies marijuana as a Schedule I drug, a category reserved for drugs that have no current acceptable medical use and a high potential for abuse. The Michael J. Fox Foundation and others have previously called for a reclassification of marijuana, which would make it easier to conduct research.

Interpretation of research results is hampered by many variables, such as lack of standardized or known doses, and variable CBD and THC concentrations. Parkinson’s research uses many different formulations (oral cannabinoids and smoked marijuana, for example) and varied doses. This difference in formulation and dosing from person to person and study to study makes it challenging to guide the use of marijuana for medical purposes. Study size and design also can limit interpretation. Most marijuana studies include small numbers of patients. When few patients test drugs, it’s less likely the group represents the larger Parkinson’s population and results (either positive or negative) can be easily applied to most people with PD. Some studies use questionnaires where people report their symptoms and marijuana use; others lack a placebo group. Results from such trials can make it difficult to determine how much potential benefit may be due to drug versus placebo effect.

What Should You Know about Medical Marijuana and Parkinson’s?
If you’re considering medical marijuana, you and your doctor should weigh the potential benefits and risks, just as you would with any therapy. In low doses, cannabinoids appear to be relatively well tolerated. But like any other drug, medical marijuana has potential side effects. These may include nausea, dizziness, weakness, hallucinations, and mood, behavior or memory/thinking (cognitive) changes. Discuss possible influences on cognition, mood and balance, especially if you are already experiencing changes in these areas. It’s unclear how and to what extent marijuana could exacerbate these symptoms.

The potential for drug interactions between marijuana and prescription or over-the-counter medications is largely unknown, but adding marijuana to a complex regimen of medications could present a risk. As when adding any new therapy, review all your medications with your doctor and pharmacist.

Risks of long-term marijuana use haven’t yet been established. Outside of clinical trials however, many years of marijuana use are associated with an increased risk of mood disorders and, particularly with smoking, lung cancer. And estimates state that about nine percent of users become addicted.

Is Medical Marijuana for You?
As of October 2019, the District of Columbia and 33 states have passed legislation allowing the use of marijuana-based products for medical purposes. The authorized medical conditions, formulations, and patient and physician requirements are different in each state. Typically patients must register in order to possess and use cannabinoids, and a physician must document an authorized condition in order for a patient to register. Under federal law, doctors cannot prescribe marijuana or cannabinoids, but certain states allow qualified doctors to issue “certifications” that permit patients to obtain medical marijuana. (Note that many doctors choose not to pursue qualification and therefore are not able to issue certifications.) Also, even if Parkinson’s is an authorized condition for use, there may be additional requirements. In New York State, for instance, a person must have PD plus at least one associated condition — extreme malnutrition, severe or chronic pain, severe nausea, seizures, or severe or persistent muscle spasms.

Talk to your doctor if you’re thinking about medical marijuana. Your personal physician can help you review the latest research, the pros and cons, and how the therapy might fit into your regimen.

What Are the Next Research Steps?
The work to date on marijuana and cannabinoids has given promising but conflicting signals on potential benefit for motor and non-motor symptoms as well as levodopa-induced dyskinesia. This therapy may represent a future treatment option for PD, but the correct dose and formulation are not clear, full side effects and drug interactions are unknown, and benefits have not been rigorously determined. Future studies should be large and well designed to provide clear data on the safety and efficacy of marijuana and cannabinoids in Parkinson’s.

Dr. Dolhun answers common questions about medical marijuana and PD.

Can Marijuana Treat Symptoms of Parkinson’s Disease?

Parkinson’s disease (PD) is a progressive, permanent condition that affects the nervous system. Over time, stiffness and slowed cognition can develop. Eventually, this can lead to more severe symptoms, such as moving and speech difficulties. You may even experience tremors as well as posture changes.

Researchers are constantly looking for new therapies that can help people manage PD symptoms and overall quality of life. Marijuana is one possible alternative treatment.

Numerous studies have been conducted on marijuana and its active components. While not entirely conclusive, the research on marijuana shows promise for people with PD. It may help with overall symptom management.

Read on to learn more about the uses of marijuana for PD.

For PD, marijuana is thought to provide numerous benefits, including:

  • pain relief
  • reduced tremors
  • better quality of sleep
  • improved overall mood
  • more ease in movement

These benefits are attributed to the muscle-relaxing and analgesic effects of marijuana.

Though marijuana can come with minor side effects, some people prefer these over some of the risk factors associated with common PD medications. Certain drugs for Parkinson’s disease can cause:

  • ankle swelling
  • blotching of the skin
  • constipation
  • diarrhea
  • hallucinations
  • insomnia
  • involuntary movements
  • memory problems
  • nausea
  • liver damage
  • problems urinating
  • sleepiness

Research into marijuana’s effects on health are prominent as more states work toward legalization. In one study published in 2014 , 22 participants with PD saw improvement in sleep, tremors, and pain within 30 minutes of smoking marijuana.

In another study published in 2010 , researchers found that cannabinoids have anti-inflammatory properties. Cannabinoids are active compounds in marijuana. These may help reduce symptoms in a variety of related diseases.

The research into potential effects of marijuana for PD is ongoing. Larger studies may need to be conducted before it’s a widely accepted treatment.

Despite the potential benefits of marijuana for people with Parkinson’s, there are also some risk factors involved. THC in marijuana can cause:

  • impaired thinking and movements
  • hallucinations
  • memory problems
  • mood changes

Smoking marijuana may have more side effects than taking it in other forms. Short-term effects are related to the smoke itself and can include lung irritation and coughing. Frequent lung infections are another possibility. Over time, marijuana smoke may lead to heart problems or exacerbate any current heart conditions, although there are no clinical studies that show a direct relationship between marijuana and cardiovascular events.

If you have depression or anxiety, using marijuana has the potential to make your symptoms worse, as some research suggests that people who smoke marijuana are diagnosed with depression more often than those who do not. However, there is no clear evidence that marijuana directly causes depression. Learn more about the effects of marijuana on your body.

Although the FDA has not recognized the marijuana plant as medicine, there are two main cannabinoids from the plant that are used for treatment: cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC).

CBD contains active ingredients from the Cannabis plant minus the THC, which is the part that makes people “high.” These compounds have the potential to decrease inflammation and reduce pain without the psychoactive effects of THC. CBD can be used to treat a variety of chronic illnesses, including Parkinson’s disease. Cannabidiol also doesn’t carry the risks of traditional marijuana smoke.

CBD may come in the form of:

  • oils
  • food products, such as candies and brownies
  • teas
  • extracts
  • waxes
  • pills

In some states, CBD can be purchased over the counter with no prescription or medical marijuana license and is considered legal if it’s produced from industrial hemp. In all states where medical marijuana is legal, CBD is covered under the same legal protections.

In the United States, medical marijuana and CBD laws vary by state. If medical marijuana is legal in your state, you’ll need to ask your doctor to fill out forms for an application to obtain a medical marijuana card. This card identifies you as being able to purchase marijuana in your state for a designated medical condition.

Medical marijuana isn’t legal in all states. It also isn’t legal in all countries. Check your local laws for more information and talk with your doctor. If it isn’t legal where you live, it may become legal in the future.

The primary goals in treating PD are to alleviate symptoms and improve quality of life. Treatment may also prevent disease progression.

If taking marijuana isn’t feasible, there are other options available. Numerous types and combinations of conventional medications may also be used. Examples include:

  • amantadine (Symmetrel), which is used in early stages
  • anticholinergics
  • carbidopa-levodopa (Sinemet)
  • catechol-o-methyltransferase (COMT) inhibitors
  • dopamine agonists
  • MAO-B inhibitors, which may help prevent dopamine levels from dropping

Most PD medications focus on motor symptoms. These treatments may not work for other symptoms, called “nonmotor” symptoms. Talk to your doctor about possible options for treating the following nonmotor symptoms of Parkinson’s:

  • anxiety
  • bladder problems
  • constipation
  • dementia
  • depression
  • difficulties with concentration and thinking
  • fatigue
  • insomnia
  • loss of libido
  • pain
  • swallowing difficulties

It’s important to note that marijuana can potentially treat both motor and nonmotor PD symptoms.

To prevent Parkinson’s from getting worse, your doctor may recommend a type of surgery called deep brain stimulation. This involves the surgical placement of new electrodes in the brain.

Currently, there’s no cure for PD. Medications can help manage your symptoms. You may also want to explore alternative therapies, including marijuana. Marijuana isn’t a feasible therapy for everyone with Parkinson’s, but if you’re interested in considering this treatment, talk to your doctor to find out if it’s a good option for you.

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