Correlation and treatment potential
Parkinson’s disease is a progressive neurodegenerative disorder. It is a dysfunction of the central nervous system (CNS) that results from the destruction, possibly immune-mediated, of dopamine-producing neurons in the area of the brain called the substantia nigra. Symptoms of the disease, which are not normally detected until substantial portions of the CNS have already been affected, include tremors while at rest, walking or balance problems, and muscle rigidity. As of today, the disease is incurable, and arresting the progression is the best clinical scenario that can be achieved.
We must first nod our heads to the people whose work and lives have made awareness of this disease common. In the 1970’s, famous neuroscientist and author Dr. Oliver Sacks, who studied the progression of Parkinson’s disease, theorized that the dopamine precursor L-DOPA, a newly synthesized pharmaceutical compound, could alleviate the symptoms of Parkinson’s and Parkinson’s-like disease. The story of his discovery and clinical trials were published in his book Awakenings, a book which was later turned into a movie starring Robin Williams as Dr. Sacks. Importantly, like Lou Gehrig and ALS, American actor Michael J. Fox, who famously played Marty McFly in the Back to the Future trilogy, is who many people think of when Parkinson’s disease comes up. He was diagnosed with Parkinson’s in 1991 at age 29, and has dedicated a significant portion of his life and funds to the betterment of Parkinson’s research and care through the Michael J. Fox Foundation.
Dr. Sacks and Michael J. Fox ensured that the plight of those suffering from Parkinson’s disease did not go unnoticed. Concomitant advances in cannabis research have revealed that it may have a role to play in the abatement of Parkinson’s-related disease symptoms. For example, an open-label study published in 2014 examined the effects of cannabis use on both motor and non-motor symptoms of Parkinson’s, and found a significant benefit for those who used cannabis in motor function, as well as improved sleep and reduced pain.  Though open-label studies, where the subjects and researchers both are aware of the treatment being given, are inherently less rigorous than a placebo-controlled study, these results provide a clinical rationale for continued investigation. Parkinson’s patients have self-reported similar findings in other published works.  Finally, the elucidation of endocannabinoid pathways inside the CNS have given further scientific credence to the therapeutic potential of cannabis in the treatment of this disease. 
The therapeutic use of cannabis in the treatment of Parkinson’s disease or its symptoms is not mainstream in any way, but that may change as future legislative changes allow for meaningful clinical testing to take place.
- Lotan, Itay, et al. “Cannabis (Medical Marijuana) Treatment for Motor and Non–Motor Symptoms of Parkinson Disease: An Open-Label Observational Study”. Clinical Neuropharmacology. 2014; 37(2): 41–44 [Times cited = 80, Journal impact factor = 2.009].
- Balash, Yacov, et al. “Medical Cannabis in Parkinson Disease: Real-Life Patients’ Experience”. Clinical Neuropharmacology. 2017; 40(6): 268–272 [Times cited = 10, Journal impact factor = 2.009].
- Benarroch, Eduardo. “Endocannabinoids in basal ganglia circuits: Implications for Parkinson disease”. Neurology. 2007; 69(3): [Times cited = 45, Journal impact factor = 8.055].
Image Credit: Flickr. PET Scan showing uptake of pharmaceutical treatment in monkey brain for the treatment of Parkinson’s disease.