Parkinson’s Disease – Medical Marijuana Research

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Parkinson’s disease is a progressive nervous system disorder that affects nearly 1 million people in the U.S. Studies have shown cannabis can slow the disease’s progression and help patients manage the symptoms associated with the disease.

Overview of Parkinson’s Disease

Parkinson’s DiseaseParkinson’s disease is a chronic, progressive disorder of the nervous system that causes the malfunction and death of nerve cells in the brain. Parkinson’s disease (PD) typically starts with a minor tremor and develops gradually, eventually causing stiffness and slowing movement. Some neurons produce dopamine, a chemical that sends messages to the part of the brain that controls movement, and as these neurons die from Parkinson’s disease, the amount of dopamine decreases and movement is subsequently affected.

While the cause of Parkinson’s disease is unknown, genes and environmental triggers likely play a role. Specific genetic mutations have been identified and having a close relative with Parkinson’s increases chances of developing the disease. Exposure to certain toxins like herbicides and pesticides could also increase risk.

Symptoms associated with Parkinson’s disease include tremors, bradykinesia (slowness of movement), rigidity (stiffness) and postural instability. Tremors can occur in the hands, arms, legs, jaw and face. Parkinson’s disease is also commonly accompanied with depression, cognitive problems, swallowing problems, sleep problems, fatigue and pain. Psychosis, a severe impairment in thinking and emotion that causes one to lose contact with reality, can also occur.

There is no cure for Parkinson’s disease. However, treatments can help to improve symptoms. Medications can be used to help manage walking, movement and tremor problems by increasing or substituting for dopamine. Surgery may eventually be required to regulate certain regions of the brain.

Findings: Effects of Cannabis on Parkinson’s Disease

Evidence suggests that cannabis could potentially slow the progression of Parkinson’s by providing neuroprotective effects. The cannabinoids found in cannabis are able to suppress the excitotoxicity, glial activation and oxidative injury that cause the degeneration of the dopamine-releasing neurons. In addition, they improve the function of cell’s mitochondria and activation of cellular debris clearance, further encouraging neuron health5,6,8,13.

Researchers have found evidence that one specific cannabinoid found in cannabis, tetrahydrocannabinol (THC), helps in the treatment of Parkinson’s disease by assisting in the prevention of damage caused by free radicals and activating a receptor that encourages the formation of new mitochondria13.

Another major cannabinoid found in cannabis, cannabidiol (CBD), has also demonstrated its ability to support the health of neural cells mitochondria, causing the researchers to conclude that CBD should be considered as a potential therapeutic option in neurodegenerative disorders like Parkinson’s because of its neuroprotective properties3,13.

Studies have also shown that cannabinoids interact with the endocannabinoid system’s cannabinoid receptors, CB1 and CB2, to modulate the release of dopamine.11

Research also shows that cannabis can help patients with Parkinson’s disease manage their symptoms. One study observed that after smoking cannabis, Parkinson’s disease patients saw significant improvements in motor disability and impairments, tremors, rigidity, bradykinesia, sleep and pain7. Additional studies have confirmed cannabis’ ability to reduce bradykinesia and tremors5,6. Most recently, a clinical trial found that cannabis significantly reduced pain and motor symptoms in Parkinson’s disease patients after 30 minutes10.

Significant improvements in well-being and quality of life scores were found in Parkinson’s disease patients that were given daily doses of CBD for one week1. One case study found that patients treated with CBD, though they didn’t see significant improvements in motor measures or general symptoms, experienced prompt and substantial reductions in the frequency of REM sleep behavior disorder events1. In one survey, despite only 4.3% of Parkinson’s disease patients responding that they used cannabis to treat their symptoms, it was ranked it as the most effective treatment option out of vitamins, prayer, massage, art therapy, music therapy and relaxation4.

In addition, CBD may help with those Parkinson’s’ disease patients experiencing psychosis. Four weeks of CBD caused Parkinson’s disease patients with psychosis to experience a significant decrease in psychotic symptoms as evaluated by the Brief Psychiatric Rating Scale and the Parkinson Psychosis Questionnaire14.

States That Have Approved Medical Marijuana for Parkinson’s Disease

Currently, 11 states have approved medical marijuana for the treatment of Parkinson’s disease. These states include Connecticut, Florida, Georgia, Illinois, Maine, Massachusetts, New Hampshire, New Mexico, New York, Ohio and Pennsylvania.

A number of other states will consider allowing medical marijuana to be used for the treatment of Parkinson’s disease with the recommendation from a physician. These states include: California (any debilitating illness where the medical use of marijuana has been recommended by a physician), Nevada (other conditions subject to approval), Oregon (other conditions subject to approval), Rhode Island (other conditions subject to approval), and Washington (any “terminal or debilitating condition”).

In Washington D.C., any condition can be approved for medical marijuana as long as a DC-licensed physician recommends the treatment.

In addition, several states have approved medical marijuana specifically to treat “chronic pain,” a symptom that can arise in people with Parkinson’s. These states include: Alaska, Arizona, California, Colorado, Delaware, Hawaii, Maine, Maryland, Michigan, Montana, New Mexico, Ohio, Oregon, Pennsylvania, Rhode Island and Vermont. The states of Nevada, New Hampshire, North Dakota, Montana, Ohio and Vermont allow medical marijuana to treat “severe pain.” The states of Arkansas, Minnesota, Ohio, Pennsylvania and Washington have approved cannabis for the treatment of “intractable pain.”

Also, 19 states have approved medical marijuana specifically for the treatment of nausea, which can develop from medications used to treat Parkinson’s. These states include: Alaska, Arizona, Arkansas, California, Colorado, Delaware, Hawaii, Maine, Maryland, Michigan, Montana, Nevada, New Hampshire, New Mexico, North Dakota, Oregon, Rhode Island, Vermont, and Washington.

Recent Studies on Cannabis’ Effect on Parkinson’s Disease
  • Smoking cannabis causes Parkinson’s disease patients to see significant improvements in tremors, rigidity and bradykinesia.
    Cannabis (medical marijuana) treatment for motor and non-motor symptoms of Parkinson disease: an open-label observational study.
  • CBD improves well-being and quality of life in Parkinson’s disease patients.
    Effects of cannabidiol in the treatment of patients with Parkinson’s disease: an exploratory double-blind trial.
  • Cannabis significantly reduced pain and motor symptoms in patients with Parkinson’s disease.
    Effect of medical cannabis on thermal quantitative measurements of pain in patients with Parkinson’s disease.


  1. Chagas, M.H., Eckeli, A.L., Zuardi, A.W., Pena-Pereira, M.A., Sobreira-Neto, M.A., Sobreira, E.T., Camilo, M.R., Bergamaschi, M.M., Schenck, C.H., Hallack, J.E., Tumas, V., and Crippa, J.A. (2014, October). Cannabidiol can improve complex sleep-related behaviours associated with rapid eye movement sleep behaviour disorder in Parkinson’s disease patients: a case serious. Journal of Clinical Pharmacy and Therapeutics, 39(5), 564-6.
  2. Chagas, M.H., Zuardi, A.W., Tumas, V., Pena-Pereira, M.A., Sobreira, E.T., Bergamaschi, M.M., dos Santos, A.C., Teixeira, A.L., Hallak, J.E., and Crippa, J.A. (2014, November). Effects of cannabidiol in the treatment of patients with Parkinson’s disease: an exploratory double-blind trial. Journal of Psychopharmacology, 29(11), 1088-98.
  3. da Silva, V.K., de Freitas, B.S., da Silva Dornelles, A., Nery, L.R., Falavigna, L., Ferreira, R.D., Bogo, M.R., Hallak, J.E., Zuardi, A.W., Crippa, J.A., and Schroder, N. (2014, February). Cannabidiol normalizes caspase 3, synaptophysin, and mitochondrial fission protein DNM1L expression levels in rats with brain iron overload: implications for neuroprotection. Molecular Neurobiology, 49(1), 222-33.
  4. Finseth, T.A., Hedeman, J.L., Brown, R.P. 2nd, Johnson, K.I., Binder, M.S., and Kluger, B.M. (2015). Self-reported efficacy of cannabis and other complementary medicine modalities by Parkinson’s disease patients in Colorado. Evidence-Based Complementary and Alternative Medicine, 2015, 874849.
  5. Garcia-Arencibia, M., Garcia, C., and Fernandez-Ruiz, J. (2009, December). Cannabinoids and Parkinson’s disease. CNS & Neurological Disorders Drug Targets, 8(6), 432-9.
  6. Lastres-Becker, I., and Fernandez-Ruiz, J. (2006). An overview of Parkinson’s disease and the cannabinoid system and possible benefits of cannabinoid-based treatments. Current Medicinal Chemistry, 13(30), 3705-18.
  7. Lotan, I., Treves, T.A., Roditi, Y., and Djaldetti, R. (2014, March-April). Cannabis (medical marijuana) treatment for motor and non-motor symptoms of Parkinson disease: an open-label observational study. Clinical Neuropharmacology, 37(2), 41-4.
  8. More, S.V., and Choi, D.K. (2015, April). Promising cannabinoid-based therapies for Parkinson’s disease: motor symptoms to neuroprotection. Molecular Neurodegeneration, 10, 17.
  9. Parkinson’s disease. (2015, July 7). Mayo Clinic. Retrieved from
  10. Shohet, A., Khlebtovsky, A., Roizen, N., Roditi, Y., and Djaldetti, R. (2016, October 10). Effect of medical cannabis on thermal quantitative measurements of pain in patients with Parkinson’s disease. European Journal of Pain, doi: 10.1002/ejp.942 [Epub ahead of print].
  11. Stampanoni Bassi, M., Sancesario, A., Morace, R., Centonze, D., and Iezzi, E. (2017, February). Cannabinoids in Parkinson’s Disease. Cannabis and Cannabinoid Research, 2(1), 21-29.
  12. What is Parkinson’s Disease? (2015). Parkinson’s Disease Foundation. Retrieved from
  13. Zeissler, M.L., Eastwood, J., Hanemann, C.O., Zajicek,J., and Carroll, C., (2013). 9-Tetrahydrocannabinol is protective through PPARy dependent mitochondrial biogenesis in a cell culture model of Parkinson’s disease. Journal of Neurology, Neurosurgery and Psychiatry, 84.
  14. Zuardi, A.W., Crippa, J.A., Hallak, J.E., Pinto, J.P., Chagas, M.H., Rodrigues, G.g., Dursun, S.M., and Tumas, V. (2009, November). Cannabidiol for the treatment of psychosis in Parkinson’s disease. Journal of Psychopharmacology, 23(8), 979-83.
  15. Zuardi, A.W., (2008, September). Cannabidiol: from an inactive cannabinoid to a drug with wide spectrum of action. Revista Brasileira De Psiquiatria, 30(3), 271-80.

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