Numerous studies have shown that the signaling of the endocannabinoid system (ECS) is influenced or affected in Parkinson's Disease (PD). Because of this, it doesn't take a huge leap of the imagination to reason that cannabinoids can perhaps have a role to play in treating PD, or at least in ameliorating its symptoms. Let's have a look to see how cannabidiol (CBD) oil for Parkinson's can be helpful.
Parkinson's disease of the nervous system, causing symptoms such as tremors, muscular rigidity or stiffness, and imprecise, slow movement. Most of the patient population are middle-aged or elderly, and the disease is progressive, meaning that it gets worse over time.
PD is caused by degeneration of the basal ganglia in the brain. The basal ganglia are a cluster of neurons situated in the midbrain, deep under the cerebral cortex. The disease is also marked by a dopamine deficiency in patients.
As with most conditions, good clinical research in the helpfulness of cannabinoids for PD is still lacking, but anecdotes tout its efficacy to help with insomnia, pain, and anxiety.
Most people diagnosed with PD battle with sleep disorders, which constitutes one of the leading causes of disability in the disease. A great percentage of these patients present with REM sleep behavior disorder, which shares many similar clinical features with PD. It is characterized by the person “acting out” vivid, intense, and sometimes violent dreams while asleep. This is because the sleep paralysis usually associated with REM sleep is incomplete in these individuals, and some muscles don't get to relax as they should during sleep. This disorder can be dangerous, as people sometimes end up hurting themselves and/or their sleep partners. Also, it greatly affects the quality of life for PD patients, because they don't get good-quality sleep.
Moreover, some researchers seem to think that REM sleep behavior disorder precedes PD. 
Not much clinical research has been conducted regarding CBD oil for Parkinson's, but the available data is indicative that CBD does make a positive difference in sleep patterns.
One prominent anecdote was delivered by Gary Griffin, erstwhile commercial airman and businessman from Colorado, who never used to consider marijuana good for anything.
"It was the devil's weed, it was awful to me," he recounts during an interview with CBD Denver.
Yet after being diagnosed with Parkinson's, his horizons opened by necessity, so he was willing to enroll in a CBD study together with his neurologist, Dr. Maureen Leehey. Taking CBD oil at the Colorado Hospital, some of Leehey's patients found an improvement in their neuromotor symptoms and also in their sleep patterns.
For Gary, the miracle didn't happen to control the tremor, which only improved slightly, but in his words:
"Once I started taking CBD oil, I never again experienced a sleepless night because I couldn't relax my muscle groups." Now, Gary is, by his own admission, a proponent of CBD oil for Parkinson's, especially the sleep disorders.
Watch an interview with himhere:
Source: YouTube Channel CBS Denver
This effect still needs to be subjected to robust clinical study, but in a small case series study, PD patients responded very well to CBD oil for this particular sleep disorder. The researchers concluded that the patients showed a prompt and substantial reduction in the frequency of REM sleep behavior disorder events—without any side effects. 
So, with CBD oil, Parkinson's-associated sleep disorders could soon be a thing of the past.
Can CBD help with the other symptoms, or even as a treatment of the disease? A preliminary study says "Perhaps," but it suggests that this can only happen effectively if CBD is administered or ingested together with another cannabinoid, tetrahydrocannabinol (THC).
The premise that THC and CBD together could possibly pose helpful in the treatment and management of PD is based on their modes of action.
Both cannabinoids are neuroprotective through their antioxidant activity, which, researchers argue, could help halt the progression of neurodegenerative diseases such as Parkinson's and Huntington's. Injury through oxidation is a known cytotoxic—or cell-destroying—mechanism, so in this sense, THC and CBD can stop the destruction of the neurons in the basal ganglia.
Also, upregulation of a certain receptor (CB2) indigenous to the endocannabinoid system has been associated with neurodegenerative diseases. "Upregulation" happens when a cell increases the number of a specific type of receptors. This is used as a mechanism to increase the cell's sensitivity to a specific compound or hormone.
Therefore, one study argues, "This CB(2) receptor up-regulation has been found in many neurodegenerative disorders including HD and PD, which supports the beneficial effects found for CB(2) receptor agonists in both disorders." CBD is a powerful CB2 agonist. 
Other experimental studies report interactions between cannabinoids and other receptor systems, but only the endocannabinoid system has, thus far, been associated with possible cannabinoid treatment of PD. As mentioned, a lot more clinical, a well-designed study is needed before conclusive pharmacologic benefits can be pronounced. 
So, all of this is limited to laboratory study, but at least one investigation showed the positive effect of medicinal marijuana on Parkinson's disease. Marijuana contains both THC and CBD.
This open-label, observational study, conducted in 2014, of 22 PD patients taking marijuana demonstrated significant improvement in their motor function:
"Analysis of specific motor symptoms revealed significant improvement after treatment in tremor...rigidity...and bradykinesia." 
Therefore, the signs are positive, but more study is needed. CBD oil for Parkinson's is definitely good for improving sleep—and to a degree for tremor reduction—but other therapeutic indications still need to be proved by science.
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