Cannabis and Parkinson’s
Earlier this year, 1,600 people with Parkinson’s and 29 health and care professionals shared their views about and experiences of using cannabis-derived products.
Here’s what they said.
When it comes to evidence of the benefits of cannabis-based products for people with Parkinson’s, the jury is definitely out.
Although lab studies have shown some promising effects, there isn’t enough evidence yet to show that cannabis-based treatments are beneficial for people with Parkinson’s. And there are very real risks.
There’s a lot more research needed, both in the lab and in clinical trials.
In fact, we’re funding a clinical trial through our Virtual Biotech right now. In a world first clinical trial, Professor Sagnik Bhattacharyya and Dr Latha Velayudhan at Kings College London (KCL) will be testing whether cannabidiol (CBD) can treat Parkinson’s psychosis symptoms.
Over the next 3.5 years, researchers will test whether Cannabidiol (CBD) helps people’s psychosis symptoms. During this trial they’re aiming to find out how safe it is, whether there are any side effects, the best way to administer it and the ideal dosage.
The legal stuff
Cannabis is a class-B controlled drug in the UK. Possessing, producing and supplying it are all against the law. ‘Supply’ includes sharing the drug with someone or giving it (even for free) to friends or relatives.
Cannabis-based products are not available on prescription for people living with Parkinson’s. And using cannabis to help with your Parkinson’s symptoms is not a valid defence in the eyes of the law.
CBD oil is available to buy legally as a food supplement. But it can’t be advertised as beneficial for medicinal purposes as there is not enough evidence currently.
Our survey results
Between January and March 2019, we asked people with Parkinson’s and health professionals to tell us about their experiences with and opinions on using cannabis-based products.
We’ve now analysed their answers and produced a short report sharing our key findings.
Our policy panel will discuss these findings at their November 2019 meeting and agree what we think as an organisation and our next steps.
How many people with Parkinson’s use cannabis?
- 59% hadn’t used cannabis-derived products before, but would consider using them to control their symptoms.
- 26% had used cannabis-derived products (16% are currently using them for their Parkinson’s and 10% have used them in the past).
- 16% hadn’t used cannabis-derived products and aren’t interested in using them in the future.
- Overwhelmingly, people with Parkinson’s would continue to use, or start using, cannabis-derived products if robust evidence became available that they’re safe and effective in treating Parkinson’s symptoms.
What products are people using?
The most common cannabis-derived product people with Parkinson’s used was CBD oil. People interested in using a cannabis-derived product in the future said this is what they’d consider using.
Where do people get cannabis from?
People who currently use cannabis-derived products, and those who had previously used them, buy them from high street shops.
However, 87% of people who hadn’t used cannabis-derived products said they would want a doctor or pharmacist to prescribe them.
What are the side effects?
Respondents who had used cannabis-derived products in the past said they didn’t experience side effects, and that the products didn’t interact with their Parkinson’s medication. This was backed up by professionals.
However, people who hadn’t used them said they were worried about potential side effects and interactions with Parkinson’s medication.
Most people currently using cannabis-derived products, or those who had used them in the past, didn’t get advice from professionals beforehand. Those who did are split on whether the advice was helpful.
Professionals reported that people with Parkinson’s regularly ask them about using cannabis-derived products. 70% of professional respondents said they offer advice.
86% of professionals didn’t feel confident about prescribing cannabis-based medicinal products for their patients. Many weren’t sure if the prescribing guidance is fit for purpose (it doesn’t specifically mention Parkinson’s).
Earlier this year, we surveyed 1,600 people with Parkinson's and 29 health professionals about using cannabis-derived products. Here are the results.
With medical marijuana now legalized in 33 states and Washington, DC, it is obvious that there is strong interest in its therapeutic properties. Researchers are testing marijuana, which is also called cannabis, as a treatment for many illnesses and diseases, including neurological conditions, with Parkinson’s disease (PD) high on the list. But despite several clinical studies, it has not been demonstrated that cannabis can directly benefit people with PD.
The Science Behind Marijuana
What is the science and pharmacology behind marijuana, and can it be used to treat Parkinson’s symptoms?
The endocannabinoid system is located in the brain and made up of cannabinoid receptors (a receptor is molecular switch on the outside of a cell that makes something happen inside a cell when activated) that are linked to neurons (brain cells) that regulate thinking and some body functions.
Researchers began to show enthusiasm to study cannabis in relation to PD after people with PD gave anecdotal reports and posted on social media as to how cannabis allegedly reduced their tremors. Some researchers think that cannabis might be neuroprotective— saving neurons from damage caused by PD.
Cannabinoids (the drug molecules in marijuana) have also been studied for use in treating other symptoms, like bradykinesia (slowness caused by PD) and dyskinesia (excess movement caused by levodopa). Despite some promising preclinical findings, researchers have not found any meaningful or conclusive benefits of cannabis for people with PD.
Researchers issue caution for people with PD who use cannabis because of its effect on thinking. PD can impair the executive function — the ability to make plans and limit risky behavior. People with a medical condition that impairs executive function should be cautious about using any medication that can compound this effect.
The Pharmacology of Cannabis
Marijuana contains more than 100 neuroactive chemicals that work with two types of cannabinoid receptors, type 1 (CB1) located in the brain and type 2 (CB2) located in the brain and peripheral immune system. Cannabinoids have powerful, indirect effects on these receptors, but researchers are unsure how. People with PD have less CB1 receptors than people who do not have PD. A boost to the CB1 receptor through an agonist, like marijuana, can improve tremors and may alleviate dyskinesia. Similarly, the other receptor, CB2, is also being studied to determine if it can modify the disease or provide neuroprotective benefits. However, a unified hypothesis does not currently exist for either receptor because there is too much conflicting data on the effectiveness of cannabinoids and these receptors.
Cannabis can contain two different types of molecules that interact with cannabinoid receptors: agonists and antagonists. An agonist is a drug that attaches to the same receptor as a natural chemical and causes the same effect. A dopamine agonist is a drug that is not dopamine, but attaches to the dopamine receptor. An antagonist is different as it attaches to the receptor, but blocks the action of the natural chemical. Medical marijuana can contain both cannabinoid agonists and antagonists. Recreational marijuana use is derived from its effects on agonists.
The varying amounts of cannabinoid agonists and antagonists in different marijuana plants makes cannabis studies difficult to conduct. When researchers study the effects of a medication, dosages are controlled and often set to a specific number of milligrams. When testing medical marijuana, the dosage administered can vary dramatically depending on the plant and method of administration.
THC is a primary component of marijuana. Cannabidiol is the other primary component. THC has a long latency of onset and cannot be easily measured for a therapeutic or medicinal dose. Medical marijuana studies primarily provide participants with THC and/or cannabidiol as a capsule, nasal spray or liquid formulation.
PD-Related Medicinal Marijuana Trials
The use of cannabinoids has been suggested to help with managing neurological and non-neurological conditions. Literature on medical marijuana is incredibly varied. Studies have not clearly supported the use of marijuana for PD. The clinical studies of cannabis as a PD treatment that have been conducted did not use the clinical trial gold standard of a double blind, placebo controlled trial design. Some studies had as few as five subjects.
While some results have been positive, the effects of medical marijuana are probably not completely understood, which is why more studies, especially those with more subjects, are needed. Most doctors don’t support study results because these studies do not meet minimum research standards.
Below are several PD-related medical marijuana studies that have been conducted to evaluate the use of cannabinoids:
- The Therapeutic Potential of Cannabinoids for Movement Disorders: clinical observations and trials of cannabinoid-based therapies suggest a possible benefit to tics and probably no benefit for tremor in dyskinesias or PD motor symptoms. Further preclinical and clinical research is needed to better characterize the pharmacological, physiological and therapeutic effects of this class of drugs in movement disorders.
- Cannabinoids Reduce Levodopa-induced Dyskinesia in Parkinson’s Disease: A Pilot Study: the authors demonstrate that nabilone, the cannabinoid receptor agonist, significantly reduces levodopa-induced dyskinesia in PD.
- Neurokinin B, Neurotensin, and Cannabinoid Receptor Antagonists and Parkinson Disease: evaluation of the effects of three antagonists on the NK3, neurotensin and cannabinoid receptors on the severity of motor symptoms and levodopa-induced dyskinesias after administration of a single dose of levodopa in 24 patients with PD. The study concluded that the drugs tested were safe, but did not improve Parkinsonian motor disability.
- The Endocannabinoid System as an Emerging Target of Pharmacotherapy: reviews the endocannabinoid system and its regulatory functions in health and disease.
Risks and Benefits for People with PD
There are risks and benefits associated with the use of cannabis for people with PD. Benefits include a possible improvement in anxiety, pain management, sleep dysfunction, weight loss and nausea. Potential adverse effects include: impaired cognition (impairment in executive function), dizziness, blurred vision, mood and behavioral changes, loss of balance and hallucinations. Chronic use of marijuana can increase risk of mood disorders and lung cancer.
Medical Marijuana and Legislation by State
Thirty-five states and Washington, DC have passed legislation allowing the use of marijuana-based products.
In some states where medical marijuana is legalized, consumers must register to possess and use cannabis. Other states require consumers to acquire a document from a physician stating that the patient has an approved condition. Under federal law doctors cannot prescribe cannabis, but many states authorize them to issue certifications that allow patients to obtain medical marijuana.
PD is listed as a qualifying condition for medical marijuana in Connecticut, Florida, Illinois, Louisiana, Massachusetts, Michigan, Mississippi, Missouri, New Hampshire, New Mexico, New York, Ohio, Pennsylvania and West Virginia.
Medical marijuana is legal in Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Illinois, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Utah, Vermont, Washington, West Virginia and Washington, DC.
Fifteen states have legalized the recreational use of marijuana, making it legal for adults over the age of 21 to legally consume marijuana without a doctor’s recommendation. Many of these states still differentiate recreational from medical marijuana. In some states, medical marijuana consumers may have access to specialized dispensaries, strains of marijuana and sales tax exemptions.
Recreational marijuana is legal in Alaska, Arizona, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Montana, New Jersey, Nevada, Oregon, South Dakota, Vermont, Washington, and Washington, DC.
Multiple states, counties or cities have decriminalized certain marijuana-related offenses. In these areas, the possession of marijuana can be met with a citation — forgoing an arrest or criminal record — or no penalty at all.
For state by state guidance on marijuana legalization, medical laws and discrimination visit Norml.org/laws.
Parkinson’s Foundation Centers of Excellence and Medicinal Marijuana
The Parkinson’s Foundation, in partnership with Northwestern University researchers, studied attitudes about cannabis at 40 Centers of Excellence. To the best of our knowledge, this is the first study to provide data on the practices, beliefs and attitudes of expert PD physicians concerning cannabis use.
The results were interesting: most experts said they knew what cannabis did, but disagreed on the details. While there is no general agreement on what the benefits might be for people with PD, the survey confirmed that cannabis is a popular subject within Parkinson’s Foundation centers as 95 percent of neurologists reported patients have asked them to prescribe it.
Cannabis study results also included:
- Only 23 percent of physicians had any formal education on the subject of cannabis (such as a course or lecture), thus 93 percent of physicians want cannabis taught in medical school.
- Physicians reported that 80 percent of their patients with PD have used cannabis.
- Only 10 percent of physicians have recommended the use of cannabis to patients with PD.
- In terms of memory: 75 percent of physicians felt that cannabis would have negative effects on short-term memory and 55 percent felt that cannabis could have negative effects on long-term memory
- Only 11 percent of physicians have recommended use of cannabis in the last year
This graph shows how physicians expect cannabis would improve, worsen, or show no effect to PD-related symptoms given their expertise and observations of patients with PD.
The study emphasized that physicians would be more apt to use medical marijuana as a treatment if it was approved through regulation instead of legislation. Nearly all medications are only approved after passing a science-based evaluation proving their effectiveness in a process overseen by the U.S. Food and Drug Administration. Since cannabis has been approved through legislation rather than regulation, there are no labels, dosage recommendations or timing instructions that physicians can reference.
Is Medical Marijuana an Option for Me?
What’s next for a person with PD who wants to know if medical marijuana is an option? “Marijuana should never be thought of as a replacement for dopaminergic and other approved therapies for PD,” said Dr. Michael S. Okun, the Parkinson’s Foundation National Medical Advisor.
Research is still needed to determine how medical marijuana should be administered and how its long-term use can affect symptoms of PD. To keep patients safe, states that legalize medical marijuana will eventually need to develop training programs for doctors and medical teams that prescribe medical marijuana. Consult your doctor to see if medical marijuana is an option for you.
The Parkinson’s Foundation Consensus Statement on the Use of Medical Cannabis for Parkinson’s Disease is designed to help guide the PD community in making informed decisions about using cannabis for Parkinson’s. The statement is based on the input from 46 experts who attended the Foundation’s first-ever medical marijuana convening. Read it now.
Page reviewed by Dr. Bhavana Patel, Movement Disorders Fellow at the University of Florida, a Parkinson’s Foundation Center of Excellence.
With medical marijuana now legalized in 33 states and Washington, DC, it is obvious that there is strong interest in its therapeutic properties. Researchers are testing marijuana, which is also called cannabis, as a treatment for many illnesses and diseases, including neurological conditions, with Parkinson's disease (PD) high on the list. But despite several clinical studies, it has not been demonstrated that cannabis can directly benefit people with PD.