Parkinson's disease (PD) is a chronic neurological disorder that gets worse with time. There is no known cure for this disease, which causes a lack of control over bodily movements, depression, cognitive decline, and more. 

This condition can be a very debilitating disorder, because it can affect eating, sleeping, and many other vital bodily functions and activities. Decades of research have been dedicated to understanding the role of dopamine and other neurotransmitters in the disease, but the genetic and environmental factors that cause people to develop PD are unknown. 

Substantial research has demonstrated the neuroprotective, antidepressant, analgesic, and antioxidative properties of cannabis. Because all of these factors are linked to Parkinson's disease, cannabis may help manage the multifaceted symptoms of this neurological condition.

Medical cannabis use could help manage the symptoms of Parkinson's disease. (Photo: Gina Coleman/Weedmaps)

Animal studies have shown that cannabinoids may play an important role in protecting against the neurodegeneration that is seen in PD. A 2011 study in the British Journal of Pharmacology demonstrates that THCV may be particularly important for this neuroprotective effect. Preventing the loss of dopamine-producing neurons is at least partially thanks to activity at the CB2 receptor, according to a 2009 study in the European Journal of Neuroscience.

A large 2004 survey of 339 PD patients revealed that cannabis relieved symptoms in 46% of the patients, who reported improvements in muscle rigidity and various aspects of motor control, including tremors. Similar motor symptom relief was found in an observational study of 22 PD patients, as reported in 2014 in the journal Clinical Neuropharmacology. This study also found that cannabis significantly improved both sleep and pain for these patients.  

There have been relatively few clinical trials examining the benefit of cannabis for Parkinson's. A 2004 randomized controlled trial of 17 PD patients, published in Neurology, failed to reveal any benefit of oral cannabis extract. However, additional clinical trials are forthcoming in Canada, where researchers from the University Health Network, Toronto will be examining the effects of cannabis oil with various amounts of THC on pain, sleep, and motor symptoms associated with Parkinson's disease. 

Actor Michael J. Fox is perhaps the most prominent Parkinson's disease patient and spokesperson. Diagnosed at 29 while he was filming “Doc Hollywood” in 1991, Fox didn't reveal his health condition to the public until 1998, seven years after the fact. Today, the acclaimed actor is not only a survivor of Parkinson's disease but also a vocal advocate for cannabis treatment.

In a 2016 interview with the luxury lifestyle magazine Haute Living, Fox explained, “I was diagnosed 25 years ago, and I was only supposed to work for another 10 years. I was supposed to be pretty much disabled by now. I'm far from it.”

A two-pronged survey focusing on Parkinson's disease and multiple sclerosis (MS) was hosted online by the Michael J. Fox Foundation and the National Multiple Sclerosis Society in 2016. Participants who used cannabis reported high levels of effectiveness and lower levels of disability on the survey, especially with regard to mood, memory, and fatigue. The survey results were subsequently published in the journal Complementary Therapeutic Medicine in 2017. 

Despite the encouraging results of early studies, not every medical expert is rushing to prescribe medical marijuana to Parkinson's patients. This resistance may be in part due to issues with federal illegality as well as the lukewarm stance of the Parkinson's Foundation, which maintains that “research is still needed to determine how medical marijuana should be administered and how its long-term use can affect symptoms of PD.”

However, a Parkinson's disease-focused media source, called Parkinson's News Today, has been more open in acknowledging the potential benefits of cannabis treatment, notably for older patients. The news source cited a 2018 study published in the European Journal of Internal Medicine that focused on 2,736 patients ages 65 and older who used cannabis for a variety of health reasons. Researchers found that nearly one-fifth of these patients discontinued or reduced their opioid usage after six months of using cannabis. 

One study shows the one-fifth of patients have discontinued or reduced their opioid usage by using cannabis. (Photo: Gina Coleman/Weedmaps)

As a result of this study, Parkinson's News Today asserted that, “medical cannabis is a safe and effective way for older people to alleviate symptoms of Parkinson's, cancer, and other diseases …The use of medical cannabis has grown significantly in recent years. Because of an aging population, the use has increased in older people in particular.”

Despite some conflicting reports about the effectiveness of cannabis for Parkinson's symptoms, there is enough promising evidence to justify additional placebo-controlled clinical trials. Because most people who have Parkinson's are older than 60, its particularly important for these patients to discuss cannabis use with their doctors, to prevent potentially dangerous drug interactions with other medications.