What is Parkinson’s disease?
PD, or Parkinson’s disease, is a degenerative brain disorder that affects motor coordination and the health of brain tissue; most cases are comorbid with dementia. There are four quintessential symptoms that separate Parkinson’s from other similar diseases:
- bradykinesia (slowness of movement)
- stiffness or rigidity, and
- difficulty maintaining balance and posture.
Parkinson’s disease is a progressive condition, like alzheimer’s and other geriatric diseases, which requires immense caretaking and often heavily involves the patient’s friends and loved ones. Researchers have linked PD to everything from the formation of plaque on neurons (similar to Alzheimer’s) to a mutation in the genetic code, to environmental factors such as exposure to toxic industrial chemicals. The general consensus among the research community is that a combination of these potentiating factors is required to produce the progression of symptoms.
All cases of Parkinson’s disease involve the degeneration of dopamine-producing neurons in a part of the brain called the substantia nigra, or black substance. This area is the only pigmented part of the brain, and the pigment that causes dark coloration is more or less a byproduct of dopamine synthesis. Interestingly, there are significantly greater quantities of both endocannabinoid ligands, namely 2-AG, and endocannabinoid receptors in the parts of the brain that are implicated in Parkinson’s.
The black layer in the image on the right is the substantia nigra. These neurons produce the dopamine that the rest of our brain uses. In PD, as seen on the left, these cells degenerate for reasons yet unknown, leading to a depletion of dopamine.
How is the endocannabinoid system (ECS) involved?
The connection between the endocannabinoid system and the manifestation of “no known cause” diseases like Parkinson’s is peculiar. When the endocannabinoid system was discovered throughout the 1990s, researchers weren’t sure of its specific biological purpose. As advances in technology have improved our research, and more research has improved our understanding, the role of our internal cannabinoid system has emerged from the shadows.
What we know is that the ECS is heavily involved in homeostasis, or the maintenance of internal biochemical conditions amidst changing external ones. It is present in almost every organ system, and endocannabinoid receptor type 1 is the most abundant receptor in the human brain. It is an inhibitory receptor, which means that its activation causes the suppression of some cellular activity, rather than causing the activity. For this reason, when our internal endocannabinoid signalling is disrupted, many negative results can occur as a result of untamed cellular activity.
In Parkinson’s disease, as mentioned above, there is an inordinate increase in the presence of the endocannabinoid system among the affected parts of Parkinsonian brain tissue. This leads researchers to believe that this increase is closely related to the development of PD. As we know, the endocannabinoid system is inhibitory, so its over-activation suggests that mechanisms which degrade protein plaque and protect dopaminergic neurons becomes suppressed due to endocannabinoid imbalance.
Can CBD and phytocannabinoids help to relieve Parkinsonian symptoms?
As research has been conducted on all aspects of cannabinoids and their interaction with humans, an over-arching theme has developed. For the most part, cannabinoids from plants (phytocannabinoids) have the opposite effect on cannabinoid receptors as that of endocannabinoids. THC is one of the only phytocannabinoids that is an agonist, or primary activator, of CB1 and CB2 receptors. CBD, CBC, and CBG are all different kinds of negative modulators, so whenever they interact with ECS receptors, they have the opposite effect of endocannabinoids. For this reason, they can modulate and improve endocannabinoid tone and signalling by restoring proper balance to this vital system.
In Parkinson’s patients, treatment with various cannabinoids has been highly beneficial in the mitigation of their symptoms. This fact has spurred an increase in research efforts as more and more people find that traditional pharmaceutical remedies are simply ineffective in many cases, because they don’t target the underlying causes of the disease. If the current research continues to be substantiated, ECS manipulation may prove to be a highly effective treatment because of the close relation between the endocannabinoid system and many of the pathological mechanisms of this still very mysterious degenerative brain disorder.