Different symptoms, different benefits?
Parkinson’s disease is a progressive neurological condition primarily affecting the motor system. People with Parkinson’s experience tremors, difficulty with speech, and have trouble getting around. While there are many treatments available that can help manage these symptoms, there is no cure or treatments that can slow the disease down.
While the disease’s motor symptoms are the most prominently recognized features of Parkinson’s, people also experience a wide range of non-motor symptoms. These include gastrointestinal issues like constipation, mood changes, pain, trouble sleeping, and fatigue. In some cases of later-stage disease, people can develop Parkinson’s disease dementia, which includes difficulty with cognition similar to Alzheimer’s disease.
Parkinson’s is very heterogeneous, meaning each person experiences different symptoms—in fact, no two cases of Parkinson’s are identical. This can make diagnosis quite tricky, as there are other conditions that present similarly. These include dementia with Lewy bodies and corticobasal syndrome, also known as a typical parkinsonian disorders.
Currently approved medications for Parkinson’s can help alleviate motor symptoms but do not address troublesome non-motor symptoms; there are also limitations to the extent by which motor symptoms are controlled over a 24-hour period. There are, therefore, significant unmet needs in Parkinson’s treatment which have led many to explore the potential for medical cannabis.
Parkinson’s results from a loss of cells in a region of the brain called the substantia nigra. These neurons produce dopamine, an important chemical messenger that plays a prominent role in movement. While the cause of this cell loss is largely unknown, it is likely due to a combination of genetics and environmental factors and, of course, their interactions.
Pre-clinical studies have indicated that cannabinoid 1 receptor antagonists (chemicals that reduce the activity of this receptor) may improve motor symptoms associated with Parkinson’s by increasing dopamine release.  Thus, the potential benefit of cannabinoids may lie in their interactions with other systems rather than within the endocannabinoid system alone. Despite promising results from pre-clinical studies, results from human studies have been mixed, possibly due to the heterogeneity of the condition. 
The key to understanding how cannabinoids can improve Parkinson’s symptoms will likely involve a more targeted approach to specific symptoms. For example, responses to a questionnaire sent to patients at the Prague Movement Disorder Centre revealed that a number of respondents reported cannabis use (85/339 people); of those, 39 people experienced some benefit from cannabis for resting tremor, bradykinesia (slowness of movements), muscle rigidity, and dyskinesias (involuntary movements). 
A study on cannabidiol (CBD), however, found no effects on motor symptoms; rather, there was an improvement in overall function and quality of life.  Other studies indicated an additional benefit of CBD in rapid eye movement (REM) sleep disorder and psychosis in people with Parkinson’s. [5-6]
While these findings require further confirmation, it’s possible that cannabis (containing delta-9-tetrahydrocannabinol and other cannabinoids) may be most effective for motor symptoms, while CBD alone could be most beneficial for non-motor symptoms—a key unmet need for people with this condition.
If you are interested in adding medical cannabis to your Parkinson’s treatment regimen, talk with your neurologist or movement disorders specialist. Parkinson’s is a qualifying condition for medical cannabis in many states where medical use is legal and may be beneficial for different symptoms.[Image]
- Bassi, M.S., et al., “Cannabinoids in Parkinson’s Disease.” Cannabis Cannabinoid Res, vol.2, no.1, 2017, pg. 21-29. (impact factor: N/A; cited by: 17)
- Kluger, B., et al., “The Therapeutic Potential of Cannabinoids for Movement Disorders.” Mov Disord, vol.30, no.3, 2015, pg. 313-327. (impact factor: 8.324; cited by: 50)
- Venderová, K., et al., “Survey on Cannabis Use in Parkinson’s Disease: Subjective Improvement of Motor Symptoms.” Mov Disord, vol.19, no.9, 2004, pg.1102-1106. (impact factor: 8.324; cited by: 89)
- Chagas, M.H., et al., “Effects of Cannabidiol in the Treatment of Patients with Parkinson’s Disease: An Exploratory Double-blind Trial.” J Psychopharmacol. vol.28, no.11, 2014, pg.1088-1098. (impact factor: 4.738; cited by: 94)
- Zuardi, A.W., et al., “Cannabidiol for the Treatment of Psychosis in Parkinson’s Disease.” J Psychopharmacol, vol.23, no.8, 2009, pg. 979-983. (impact factor: 4.738; cited by: 135)
- Chagas, M.H., et al., “Cannabidiol Can Improve Complex Sleep-related Behaviours associated with Rapid Eye Movement Sleep Behaviour Disorder in Parkinson’s Disease Patients: A Case Series.” J Clin Pharm Ther, vol.39, no.5, 2014, pg. 564-566. (impact factor: 1.668; cited by: 74)