Ask the Experts: The Challenges of Using Marijuana as a Parkinson’s Treatment, Part 1

Medical marijuana, or cannabis, is one of the most popular topics among the Parkinson’s disease (PD) community ― for people with PD, health professionals and researchers, alike. Earlier this year, the Parkinson’s Foundation hosted its first-ever convening on marijuana and Parkinson’s. Among the 46 attendees, of which 17 gave presentations, there was a reoccurring theme: what are the biggest hurdles the PD community faces when it comes to medical marijuana?  

This is the first article in a two-part series. Read part two here.

Treating Parkinson’s Symptoms with Cannabis

There is not enough evidence yet to support that medical marijuana can help manage Parkinson’s symptoms, however there are studies on the topic. Unfortunately, they have mixed results. Generally, the studies have been small and some with no control groups. The effects of medical marijuana are not completely understood, especially in the PD population. The bottom line is that more studies are needed, specifically larger and more rigorously conducted studies.

Based on some observational studies, cannabinoids (the active molecules in marijuana) may potentially benefit some non-motor symptoms of PD including pain, anxiety, sleep problems (insomnia, RBD, RLS), weight loss and nausea. Potential adverse effects include dizziness, blurring of vision, loss of balance, mood and behavioral changes, hallucinations, and impaired cognition and motivation. Better studies are necessary to confirm these benefit and adverse effects for people with PD.

Controlled clinical trials of cannabinoids (where some people receive the drug and some do not) have  reported mixed results for treating motor symptoms and levodopa-induced dyskinesia as well as improving quality of life.

While stories and videos exist showing that marijuana can treat PD symptoms, the challenge is showing that cannabis is better and safer than treatments that are currently available. A recent survey shows that the health community does not have a consensus on using cannabis as a treatment. This reflects lack of data, knowledge and training on the subject.

Future studies about medical marijuana and Parkinson’s should follow the highest standards of clinical trials to focus on:

• Delivery type: do specific strains, soft gels, tinctures (alcohol-based cannabis extract), e-liquid (vapor), topicals, infused food, flower products, inhalers and patches treat symptoms differently and have different side effect profiles?
• Dosage: what is the minimum dosage to guarantee effectiveness, what is the maximum dose tolerated and what dose will have a sustained benefit? Furthermore, how does this differ by strain and formulation?
• Effect on motor vs non-motor symptoms: which symptoms can improve, worsen or stay the same with cannabis use?
• Interaction with PD medications: how does cannabis interact with medications taken for PD symptoms?
• Key component: What components of cannabis/marijuana provide the best response in PD with the least risk of side effects?  What is the optimal CBD (Cannabidiol) to THC ratio?
• PD-specific side effects: are people with PD uniquely susceptible to certain side effects that are not seen in the general population?
• Population: studies that involve participants in difference stages of the disease.

Lastly, there needs to be a widespread physician education on using cannabis as a treatment ― almost all physicians surveyed agreed that medical school curriculums should include education on cannabis.

→ Danny Bega, MD, MSCI, from Northwestern University Feinberg School of Medicine; Joseph Jankovic, MD, from Baylor College of Medicine; and Karl Kieburtz, MD, MPH, from the University of Rochester, spoke about this topic at the marijuana convening.

Potential Drug Interactions

One surprising fact shared at the meeting is that cannabis-based products have the potential to interact with other medications. Given that people with Parkinson’s may be on multiple medications for other conditions, it is important to be aware of these interactions to avoid complications.

Epidiolex® is the first FDA-approved cannabinoid prescription drug. It is an oral solution of cannabidiol most commonly used to treat rare forms of epilepsy. It has been shown to have interactions with many anti-seizure medications, some antibiotics and medications for lowering cholesterol, pain, anxiety, depression and blood pressure. In some cases, Epidiolex can make these medications more or less potent. In other cases, these medications can make Epidiolex more or less potent. Because Epidiolex largely contains cannabidiol, there is the possibility that other cannabis-based products may also interact with medications in a similar way.

Delta-9-tetrahydrocannibinol (THC) is the primary psychoactive component of marijuana (the part that gives a “high”). It can take a long time to take effect and cannot be easily measured for a therapeutic or medicinal dose. THC can also interact with certain medications such as valproic acid (for bipolar disorder, seizures, and migraines) and can result in increased psychoactive effects of marijuana.

Medical marijuana can be taken in an edible form. Care should be taken with this form, as it takes longer to feel an effect and lasts longer (4-8 hours as opposed to 2-3 hours for smoking or vaporizing). Often, because the effects are slow, people increase their dose, eating more, which can be dangerous. Edibles may also have more toxicity than smoked marijuana, because they are broken down by the liver into more toxic chemicals.

→ Jacqueline Bainbridge, PharmD, FCCP, MSCS, from the University of Colorado, spoke about this topic at the marijuana convening.

The medical marijuana convening brought together a diverse group of experts from academia, clinics, industry, government and the Parkinson's community to establish a consensus on medical marijuana use in PD. The Parkinson’s Foundation will publish its findings on the convening in summer 2020. 

Learn more about Parkinson’s and marijuana at Parkinson.org/Marijuana.