CBD Use in Parkinson’s Disease Therapy

Recent research in the field of medical cannabis suggests that, in addition to metabolic imbalances, dysfunctions in the body’s endocannabinoid system may significantly influence the symptoms of Parkinson’s disease (PD). New findings also show that certain active compounds in cannabis, particularly CBD, THC, and THCV, may not only slow the progression of symptoms but even reverse them.

Key Points

• Disruptions in the endocannabinoid system may contribute to Parkinson’s disease symptoms.
• Parkinson’s progression leads to loss of muscle and limb control after about 60–80% of nerve connections in movement-related brain regions are destroyed.
• Digestive system imbalances affecting nutrient absorption can impact the development and severity of PD symptoms.
• Cannabinoids have shown effectiveness in preventing PD symptom progression due to their anti-inflammatory and antioxidant properties.
• Different combinations of THC, CBD, and THCV can have significant therapeutic effects on specific PD symptoms.

A year ago, researchers at the University of Louisville’s medical school in Kentucky discovered that CBD, in addition to activating known endocannabinoid receptors, also affects a previously unidentified protein that may positively impact certain PD symptoms. At a symposium in Montreal, scientists Zhao-Hui Song and Alyssa Laun presented evidence that CBD influences a group of G-protein-coupled receptors called GPR6, which are highly concentrated in the brain’s basal ganglia. This receptor, discovered in the 1990s, was long considered an “orphan receptor” because no activating substance had been found.

Further study revealed that CBD’s ability to block this receptor increases dopamine production—a key neurotransmitter involved in nerve signal transmission. This property could be useful in treating neurodegenerative symptoms typical of late-stage PD, where dopamine-producing neurons are destroyed. Preliminary animal studies by this team have shown practical effects in alleviating neurodegenerative PD symptoms.

According to the World Health Organization, at least 10 million people worldwide suffer from various stages of PD, with about one million in the U.S. After Alzheimer’s, PD is the second most common age-related neurodegenerative disease, with 96% of cases diagnosed in people aged 50 and older. The disease is 1.5 times more common in older men than women. Without palliative therapy, PD rapidly destroys nerve connections in the brain’s motor centers, leading to loss of bodily control. In late stages, patients can become “trapped” in their bodies, unable to consciously control their muscles.

Dopamine Depletion in Parkinson’s Disease

As PD progresses, it destroys about 60–80% of neurons in the brain regions responsible for movement. Not only are connecting neurons lost, but so are dopamine-producing cells, making it difficult for the brain to replace damaged cells. This stage is marked by noticeable symptoms: tremors in limbs or facial muscles, muscle numbness or stiffness, slow and awkward movement (hypokinesia), and loss of coordination.

Other symptoms include reduced facial expressiveness, confusion or dementia, chronic fatigue, sleep disturbances, depression, constipation, urinary problems, mood swings, and cognitive decline. Brain injuries and exposure to certain pesticides (notably the herbicide paraquat) increase PD risk. Paraquat, used in U.S. anti-drug operations, is functionally similar to the neurotoxin MPTP, which is linked to rapid PD development.

Late-stage PD brains contain high concentrations of “Lewy bodies”—protein plaques that are neurotoxic and cannot be removed by medication. These plaques cause neuron dysfunction and death, leading to cognitive decline and loss of motor control. Early symptoms often involve cognitive and emotional changes rather than motor dysfunction. The American Parkinson Disease Association notes that motor problems signal active neuron death and the onset of the disease’s critical stage. Therefore, therapy should begin before these symptoms appear.

Currently, the only somewhat effective treatment is oral levodopa, a synthetic dopamine analog. Unfortunately, long-term use can accelerate neuron destruction. There is no cure, but cannabinoids’ neuroprotective effects may be key to future treatments.

The Brain-Gut Connection in Parkinson’s Disease

One leading theory is that PD symptoms originate from dysfunction in two nervous system parts: the enteric nervous system (controlling the gut) and the medulla oblongata (especially the olfactory bulb). Research into gut microbiota suggests that mitochondrial dysfunction in gut wall cells may also play a role.

The gut microbiota—comprising bacteria, viruses, and other microorganisms—significantly affects both gut and brain health. Studies show a link between gut microbiota and the endocannabinoid system: gut bacteria influence endocannabinoid receptor activity, which in turn affects nerve signal transmission between the gut and central nervous system. Thus, gut dysfunction can directly impact brain function and the endocannabinoid system.

The enteric nervous system, sometimes called the “second brain,” is a dense network of neurons throughout the digestive tract. Some nutrients are immediately used to generate new neurons, replacing those in both the gut and brain. Neurons in the gut also trigger inflammation as a defense against injury and pathogens. Healthy gut microbiota not only aids digestion but also modulates the central nervous system, including neuron replacement in the brain. An imbalance—fewer beneficial bacteria and more harmful ones—can increase gut permeability, disrupt the immune and endocannabinoid systems, and cause further dysfunction. This phenomenon is known as increased intestinal permeability.

Recent studies show that increased gut permeability, especially in the small intestine, can accelerate PD symptom progression. According to the European Journal of Pharmacology, this is due to impaired neuron synthesis in the enteric nervous system and inflammation from immune responses in gut tissues, disrupting the natural connection between the digestive system and brain.

Mitochondria, Microbiota, and Cannabis

Problems in the gut’s nervous system are rooted in mitochondrial dysfunction. Mitochondria, present in nearly every cell except red blood cells, generate energy and regulate cell repair and death. Dysfunction leads to oxidative stress, accelerating cell destruction. This stress often results from an imbalance in gut flora: harmful bacteria entering gut wall cells negatively affect mitochondria. As digestive tract cells are damaged, patients may develop neurological (Parkinson’s, Alzheimer’s) and metabolic diseases (obesity, type 2 diabetes).

Given the link between nervous and metabolic systems, doctors believe that modulating gut microbiota could help prevent or reduce neurodegenerative symptoms. Cannabis’s effectiveness in this type of therapy has been noted since 1888, when neurologist Sir William Gowers observed that cannabis use reduced tremors in elderly patients. In his work “A Manual of Diseases of the Nervous System,” Gowers reported that oral cannabis extracts temporarily relieved tremors, and year-long use sometimes eliminated them.

Modern research confirms Gowers’ findings, showing that cannabis not only reduces inflammation in the digestive system but also protects brain tissue, preventing neuropathic disease progression. U.S. federal preclinical trials in 1998 showed that both CBD and THC have significant antioxidant and neuroprotective properties, suggesting their use in slowing and treating major neurodegenerative diseases like Parkinson’s, Alzheimer’s, and some forms of dementia.

Cannabis Use in Parkinson’s Disease Therapy

Although clinical trials of cannabis for PD have been limited due to legal restrictions (which may soon change with legalization in Canada), most studies agree that cannabinoids are among the most effective available means to slow neurodegenerative disease progression and even reverse some negative effects. THC, CBD, and THCV may all be effective in treating PD’s impact on the brain. Further research is needed to determine whether the neuroprotective effect comes from specific cannabinoids or their combinations at certain concentrations.

Anecdotal reports from therapeutic cannabis users indicate that certain oil combinations—especially those high in cannabinoid acids (precursors to active cannabinoids found in raw plant material)—are highly effective in suppressing tremors and other motor symptoms in PD patients. These include THCA and CBDA, which are non-psychoactive analogs of THC and CBD. These acids “activate” over time or when heated. Cannabinoid acids remain understudied, but doctors believe they may have strong anti-inflammatory and therapeutic effects, potentially useful for epilepsy and cancer treatment.

Overall, patients using cannabis for PD report high effectiveness in treating motor symptoms. In 2004, the Prague-based European Movement Disorder Society published a survey showing that about 45% of European respondents found cannabis and its extracts highly effective in relieving neurodegenerative symptoms affecting the brain’s motor centers.

Expert Opinions and Dosage Recommendations

Doctors specializing in cannabis medicine note that simply consuming cannabis does not guarantee maximum effectiveness for PD symptoms, due to genetic and physiological differences among patients. For example, Dr. Bonni Goldstein writes in her book “Cannabis Revealed” (2016):

“In my experience, different PD patients benefit from different cannabis oil blends. The overall therapeutic effect also depends on the method of consumption. For some, smoking or vaporizing pure THC extracts suppressed tremors. For others, sublingual CBD extracts worked. Still others benefited from oral CBD and THC mixtures. The most effective dosage and blend can only be determined through experimentation. Therefore, whether under medical supervision or self-medicating, start with low doses, especially with high-THC products. Unfortunately, the effects of another promising cannabinoid, THCV, are not well studied due to the lack of high-THCV cannabis strains.”

Dr. Juan Sanchez-Ramos, a leading researcher in experimental therapies for neurological movement disorders and director of the Parkinson’s Research Foundation, advises that for maximum therapeutic effect, cannabis with equal THC and CBD concentrations should be used. In his book “Cannabinoids in Movement Disorders,” co-authored with Dr. Briony Catlow, he describes protocols for calculating minimum effective doses of cannabinoid oils used in PD therapy. Dr. Ethan Russo, another recognized cannabis medicine expert, has personally verified the effectiveness of these cannabinoid blends.

• Daily use of up to 300 mg of pure CBD improved mood and overall well-being in PD patients, but did not significantly affect motor symptoms long-term, according to the Unified Parkinson’s Disease Rating Scale.
• Daily smoking of about 0.5 grams of cannabis flowers with equal CBD and THC content significantly reduced tremors and motor slowing, improving symptoms both during wakefulness and sleep, and enhancing sleep quality and overall tone.
• Using 150 mg of CBD extract, titrated over four weeks, noticeably improved motor symptoms and emotional well-being, reducing aggression, confusion, and psychosis related to PD.
• Oral CBD oil doses of 75–300 mg significantly improved sleep quality and increased REM sleep duration.

Minimum Effective Dose of Cannabinoids

The minimum effective (threshold) dose of cannabinoids depends on individual factors. When preparing blends, Dr. Ramos recommends mixing THC and CBD in equal proportions for the best and longest-lasting effect on PD’s physical and psychological symptoms. (Note: For patients with severe sleep disorders, a higher THC ratio may be beneficial, as THC improves sleep quality and duration.)

Dr. Russo adds: “For most new users, about 2.5 mg of THC is a sufficient minimum active dose. A 5 mg dose is standard, while 10 mg is considered high and may be excessive even for experienced users.”