Medical marijuana and parkinson’s

Medical Marijuana

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.

Delta-9-tetrahydrocannibinol (THC)

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

Washington, DC, and 33 states passed legislation allowing the use of marijuana-based products for medical purposes. In some states patients must register to possess and use cannabis. Other states require patients 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 a qualifying condition for medical marijuana in: Connecticut, Florida, Illinois, Louisiana, Massachusetts, Michigan, Missouri, New Hampshire, New Mexico, New York, Ohio, Pennsylvania and Vermont.

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 Director.

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.

Page reviewed by Dr. Bhavana Patel, Movement Disorders Fellow at the University of Florida, a Parkinson’s Foundation Center of Excellence.

Does Marijuana Help Parkinson’s?

Does marijuana help Parkinson’s and what are the reasons people believe it might?

With Parkinson’s being the second most common neurological disorder among people in the U.S., it’s no surprise that a lot of research is being done into how to help patients. There has been research recently that specifically looks at marijuana and Parkinson’s.

There are a few specific ways marijuana and Parkinson’s may have a beneficial relationship with one another.

Marijuana has anti-inflammatory and antioxidant properties, and researchers believe this may help prevent neuron damage. This is important with Parkinson’s because inflammation may be responsible for causing damage to brain neurons that produce dopamine, and that’s one of the contributors to the symptoms of Parkinson’s. If marijuana could slow some of the neuron damage in the brain, it could also slow the progression of Parkinson’s.

Other benefits of marijuana and Parkinson’s together can include pain management and help with symptoms like sleep problems and nausea. Marijuana may help people with Parkinson’s enjoy easier movement because it has muscle relaxing properties as well.

At the same time, with marijuana and Parkinson’s there are risks. One of the biggest risks is that marijuana can potentially reduce dopamine levels in the brain, so researchers are looking at how they could accommodate this in the concept of marijuana and Parkinson’s.

Possible downfalls to consider with marijuana and Parkinson’s can include the mood and behavioral changes that can result from the use of marijuana, as well as loss of balance and the risk of lung cancer that comes with chronic marijuana use.

With these adverse effects in mind, it may be possible that researchers start to look at different ways to get patients with Parkinson’s the benefits of marijuana, without having them smoke it or become high. One idea might be the use of CBD, which is a nonpsychoactive component of marijuana that has many therapeutic benefits but doesn’t cause a person to become high. CBD isn’t smoked and is available in many different forms including in oils, food products, teas, and extracts.
In many states, CBD can be purchased without a prescription, so it could provide more options for people in terms of marijuana and Parkinson’s.

Can Cannabis Help Patients With Parkinson’s Disease?

VANCOUVER—Anecdotal reports, patient surveys, and studies have suggested that cannabis may help treat motor and nonmotor symptoms of Parkinson’s disease. Two studies presented at the 21st International Congress of Parkinson’s Disease and Movement Disorders further explored this possibility and assessed the effects of oral cannabidiol (CBD) and inhaled cannabis in patients with Parkinson’s disease.


Maureen A. Leehey, MD, Professor of Neurology and Chief of the Movement Disorders Division at the University of Colorado in Aurora, and colleagues conducted a phase II, open-label, dose-escalation study to evaluate the safety and tolerability of CBD (Epidiolex) in Parkinson’s disease. In addition, the researchers looked at secondary efficacy measures, including change in tremor, cognition, anxiety, psychosis, sleep, daytime sleepiness, mood, fatigue, and pain.

Maureen A. Leehey, MD

The researchers enrolled 13 patients who had a rest tremor amplitude score of 2 or greater on item 3.17 of the Unified Parkinson’s Disease Rating Scale (UPDRS). They excluded patients who had taken cannabinoids in the previous 30 days or had a history of drug or alcohol dependence.

Over a 31-day treatment period, patients received 5-, 7.5-, 10-, 15-, and 20-mg/kg/day doses of CBD. They received the highest dose on days 17–31. Patients had clinic visits at screening, baseline, and after the 31-day treatment period. Of the 13 patients enrolled, one failed the screening visit, another patient did not start the study drug, and another patient was on the study drug for two days. The 10 remaining patients were included in the adverse events analysis. Adverse events were mostly mild to moderate and included fatigue, diarrhea, somnolence, elevated liver enzymes, and dizziness. Three of the 10 patients dropped out of the study due to intolerance. One of the three patients had an allergic reaction and two had abdominal pain. There were no serious adverse events.

Among the seven patients who completed the treatment period and were included in the efficacy analysis, mean total UPDRS score significantly decreased from 45.9 at baseline to 36.4 at the final visit. UPDRS motor score significantly decreased from 27.3 to 20.3. Mean rigidity subscore significantly decreased from 9.14 to 6.29. In addition, data hinted that CBD treatment might have reduced pain and irritability, the researchers said.

These preliminary results indicate that CBD is tolerated, safe, and has beneficial effects in Parkinson’s disease, Dr. Leehey and colleagues said. The investigators next plan to conduct a crossover, double-blind, randomized controlled trial with 50 subjects.

Inhaled Cannabis

Laurie K. Mischley, ND, PhD, MPH, Associate Clinical Investigator at Bastyr University Research Institute in Kenmore, Washington, and colleagues evaluated the effect of inhaled cannabis on Parkinson’s disease tremor using motion sensors and qualitative interviews.

The study included patients with Parkinson’s disease who used cannabis in the state of Washington. Patients wore a movement monitor for two weeks and logged their cannabis use in a journal. Sensors recorded the frequency and amplitude of tremor during waking hours, and participants pressed a button on the motion sensor every time they used cannabis. The researchers compared tremor duration and magnitude in the hour before and after inhaled cannabis use. After two weeks, interviewers asked participants standardized, open-ended, nonleading questions about their perception of the effects of cannabis on their symptoms.

The 10 patients for whom they had data had a mean age of 60 (range, 40 to 74) and a mean time since diagnosis of 6.3 years. Among four participants who had more than 10 cannabis exposures and a measurable tremor more than 2% of the time in the hour before cannabis use during the study, the percent of the time with detected tremor significantly decreased in the hour after use. Sensor data suggested that tremor reduction may have been sustained for three hours after exposure to cannabis, the researchers said. “In those with a persistent tremor, there was a consistent decrease in the tremor persistence and in detected tremor magnitude following cannabis use,” the investigators said.

During the follow-up interview, nine of the 10 participants thought that cannabis helped their symptoms, and one patient thought it worsened symptoms. “The one participant who reported cannabis worsening symptoms specifically described, ‘sometimes it speeds up the tremor at the start’ but ‘then it relaxes it,’” the researchers said.

Side effects reported by patients included sleepiness, sluggishness, concerns about social stigma and driving, short-term memory, and dry throat.

“Improved sleep was an unsolicited theme during the qualitative interviews, with 60% of individuals reporting improvements,” Dr. Mischley and colleagues said. “The qualitative interviews suggest patients perceive cannabis to have therapeutic potential for Parkinson’s disease symptom management. These data suggest further investigation of cannabis for impaired sleep is warranted.”

The researchers noted that most subjects had a mild, intermittent tremor that was not reliably detected by the motion sensors. Future studies should enroll subjects with more pronounced tremor and use consistent cannabis strains, doses, and delivery systems, they said.

—Jake Remaly

Suggested Reading

Chagas MH, Zuardi AW, Tumas V, et al. Effects of cannabidiol in the treatment of patients with Parkinson’s disease: an exploratory double-blind trial. J Psychopharmacol. 2014;28(11):1088-1098.

Finseth TA, Hedeman JL, Brown RP 2nd, et al. Self-reported efficacy of cannabis and other complementary medicine modalities by Parkinson’s disease patients in Colorado. Evid Based Complement Alternat Med. 2015;2015:874849.

Koppel BS, Brust JC, Fife T, et al. Systematic review: efficacy and safety of medical marijuana in selected neurologic disorders: report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology. 2014; 82(17):1556-1563.

Venderová K, Ruzicka E, Vorísek V, Visnovský P. Survey on cannabis use in Parkinson’s disease: subjective improvement of motor symptoms. Mov Disord. 2004;19(9):1102-1106.

Medical Marijuana and Parkinson’s Disease: Is It Safe?

Interest in using marijuana to treat the symptoms of Parkinson’s disease has grown in recent years as 33 states and the District of Columbia have legalized it for medical use.

Although the federal government has not approved medical marijuana itself, the U.S. Food and Drug Administration (FDA) has authorized some therapies that use specific marijuana components.

the FDA has given it’s okay for the THC-based drugs Marinol (dronabinol) and Cesamet (nabilone) to ease nausea during cancer treatment and stimulate appetite. THC, or tetrahydrocannabinol, is an active component in cannabis known to effect mood, behavior, and thinking.

The FDA has also greenlighted the use of CBD (cannabidiol) in a medication for childhood epilepsy called Epidiolex. CBD differs from THC in that it does not produce mind-altering effects.

Known as cannabinoids, CBD and THC act on cannabinoid receptors in the brain that regulate body functions and have been shown to play a role in Parkinson’s, according to an article published in 2017 in the journal Cannibis and Cannabinoid Research. Still, the federal government has yet sign off on any marijuana-based formulas that might help the symptoms of this neurological disorder.

Should I Use Medical Marijuana if I Have Parkinson’s?

As more states have signed up to legalize medical cannabis, patients have increasingly been exploring it as a way to treat their Parkinson’s symptoms. Some who may have found standard drugs to be insufficient turn to marijuana to help sleep, lower anxiety, or reduce tremors, according to the Parkinson’s Foundation.

Robert Duarte, MD, director of Northwell Health’s Pain Center in Great Neck, New York, treats several patients with Parkinson’s who have tried medical cannabis to alleviate pain-related problems.

“I have also seen it work on insomnia and anxiety,” he says. “If you’re sleeping better and have less anxiety, there is definitely a relationship between that and improving your tremor.”

But marijuana doesn’t work for everyone, and doctors have to rely on educated guesswork to recommend cannabis-based products.

“The problem is there are no standards for dosing or manufacturing different forms of medical cannabis,” says James Beck, PhD, chief scientific officer with the Parkinson’s Foundation. “Some people equate access to efficacy. Just because you can gain access to medical marijuana through legalization changes in different states doesn’t mean that it’s effective for a disease.”

Rebecca Gilbert, MD, PhD, chief scientific officer for the American Parkinson Disease Association in New York City, knows many Parkinson’s patients who have experimented with medical cannabis and had mixed results.

“It’s not a panacea. I have many patients who have tried it, and said it did not help sleep, tremors, or cramping,” she says. “But there is a subset of patients who find it’s useful, and we need to better understand who it’s useful for.”

Benefits and Risks of Using Medical Marijuana

The decision to use medical marijuana comes down to an individual choice based on weighing the pros and cons.

The Parkinson’s Foundation reports that some research has found cannabis to be neuroprotective, offering potential guard against damaging neurons. The cannabinoids may protect brain cells through antioxidant and anti-inflammatory properties, notes the Michael J. Fox Foundation.

In addition to possible sleep, anxiety, and tremor benefits, patients may find that it relaxes muscles and makes movement easier. One of the symptoms of Parkinson’s is rigidity from a tightening of the muscles. It may also help with loss of appetite.

Because dosing can be difficult, potency of the cannabis can pose risks. Parkinson’s patients can have trouble with cognition, and strong marijuana can cause problems with learning, memory, and thinking. If a person gets too high, he or she can feel overanxious and paranoid, and have difficulty functioning at all. If the product is too strong, the user may experience hallucinations or delusions, according to Dr. Beck.

Dr. Duarte advises that you don’t want to give a THC component to anyone who is at risk of psychosis.

Sustained marijuana use may raise blood pressure, according to a study published in August 2017 in the Journal of Hypertension, and Beck cautions that the product may also cause blood pressure to drop dangerously low.

“Low blood pressure can lead to a fall, which can be disastrous. It can lead to head injuries, a broken hip, or even death,” he says.

Dr. Gilbert suggests that patients interested in trying medical marijuana consult with a physician and review their response with the doctor.

Attitudes Toward Marijuana Use

Some patients who might find benefits from marijuana may still feel a stigma surrounding the product, noted an article published in November 2018 in the National Pain Report. It can be difficult to accept the idea that the once-illegal product is now legal and accepted in many states. Some family and friends may still judge users negatively.

“Some people are taught you should never do marijuana — it hurts people and makes you dopey,” says Duarte.

On the other hand, Gilbert believes many users embrace the product as a natural, do-it-yourself remedy. She expects that more scientific study would only improve its respectability.

Clinical Trials and Research With CBD and THC

So far, studies have been minimal and no trial has definitively found that it works to improve the disease.

“There are lot of combinations out there of THC and CBD, but not a single one has been fully tested for any symptom of Parkinson’s,” says Gilbert.

As medical marijuana has become more accepted, however, the research tide may be turning.

In fiscal year 2017, the National Institutes of Health supported 330 projects totaling almost $140 million on cannabinoid research. Within this investment, 70 projects ($36 million) examined therapeutic properties of cannabinoids, and 26 projects ($15 million) focused on CBD.

The Parkinson’s Foundation lists a handful of investigations that have evaluated the effects of cannabinoids on the disorder. In a study published in March 2015 in the journal Movement Disorders, scientists analyzed the therapeutic potential of cannabinoids for movement disorders but didn’t find any conclusive proof that marijuana helped. That investigation summarized several other studies on the topic.

A report published in January 2017 by the National Academies of Science, Engineering, and Medicine reviewed 10,000 scientific abstracts regarding marijuana’s effect on health, and concluded there was not enough evidence to support using medical marijuana for Parkinson’s.

“Medical cannabis is here and it is going to be utilized, but we need more research to provide guidelines,” says Beck. “Hopefully we’ll get to a point where we will know how to utilize marijuana in a safe manner.”

Senior Citizens, Marijuana and Parkinson’s: What I’ve Learned

  • The biggest question of all, setting aside the idea of its efficacy, is this: Is it dangerous for people with Parkinson’s? 
  • My doctor said, “There’s some evidence of loss of cognitive skills for people with Parkinson’s. It’s probably okay in the short-term, but the long-term is questionable.” 

    Since I’m 75-years old, long-term effects aren’t as important to me now as they may have been twenty years ago; so, what he said didn’t deter me.

    My thoughts after researching and studying marijuana and its use for people with Parkinson’s is that even legal marijuana is the wild west. Federal, state and local laws conflict; there is very little scientific evidence confirming its usefulness; and even if FDA standards are not met, local and state governments are approving new stores  and dispensaries. 

    On the individual side of things, there’s a significant number of anecdotes that tell the same story: “It worked for me and I’m still healthy.” 

    So, while the lack of scientific research made me skeptical, I decided to go shopping anyway and find out for myself. 

    In the next post in this series, I’ll talk about my first trip to a marijuana dispensary.

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