In a rat model of Parkinson’s disease, Italian researchers found that CBD treatments helped improve motor performance, reduced the formation of brain lesions, and dampened brain inflammation.
The research comes from the University of Pavia and the IRCCS Modino Foundation in collaboration with a Swiss pharmaceutical company, Linnea. The team found that consistent treatments with CBD improved health outcomes for rats with Parkinson’s disease-like symptoms, suggesting it may offer treatment potential in human patients as well.
Their findings support several other pre-clinical and clinical studies that show a potential for CBD in treating Parkinson’s disease.
“Parkinson’s disease is a progressive movement disorder and its prevalence in the population is rapidly rising,” the study authors explained. “The number of individuals affected by Parkinson’s disease was estimated to have more than doubled globally from 1990 to 2016.”
Many major symptoms of Parkinson’s disease involve the decline of motor skills, such as developing tremors and experiencing troubles moving or walking. These symptoms slowly worsen as brain damage builds over time.
Study authors explained that part of the disease involves the inappropriate activation of immune cells in the brain, driving unneeded inflammation leading to damage. This damage causes the loss of important neurons that produce dopamine, a chemical required for coordinating movement and memory.
However, most current pharmacological treatments fail to target this actual cause.
“Current pharmacological treatments of Parkinson’s disease are essentially focused on alleviating the characteristic motor symptoms by compensating the loss of dopamine,” the study authors said. “Without affecting the progression of the disease.”
CBD Reduces and Improves Motor Functions in Rats and Reduces Brain Inflammation
In the study, researchers used a chemical to surgically introduce progressive brain damage in rats – mirroring Parkinson’s disease.
Researchers found that the surgery caused a 70% loss of important dopamine-producing neurons in the brain after 28 days. Loss of these neurons will mean a reduction in the amount of dopamine produced; a similar loss in dopamine is seen in most Parkinson’s patients.
However, animals treated with CBD daily for the 28 days after the surgery lost 21% fewer neurons, demonstrating that CBD can actively protect the brain against damage.
This protective effect of CBD also led to improved motor skills in the animals.
Rats after the surgery typically prefer to use their forepaw controlled by the healthier side of the brain, rather than the damaged or “parkinsonized” side which is harder for the animal to control.
However, the researchers found that the animals treated with CBD showed less of a preference, suggesting that the CBD may have helped them retain more control over their movements.
When the research team looked to see how CBD affected brain inflammation – a major cause of Parkinson’s disease – they found that CBD treatment raised the levels of several protective proteins including TRPV1 and CNTF.
These two proteins have been shown in past studies to reduce inflammation and boost the survival of essential dopamine-producing neurons.
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Experiments Support Other Studies Demonstrating Potential for CBD to Treat Parkinson’s
The identification of new therapeutic strategies capable of slowing down or counteracting the decline in brain function that characterizes Parkinson’s disease “is one of the major challenges in this field” the research team said.
In recent years, interest in the neuroprotective effects of various natural compounds from cannabis has caught the eye of the scientific community.
“In particular, CBD … shows anti-inflammatory and antioxidant actions,” the study authors explained. “Which make it a potential and promising candidate in [Parkinson’s disease].”
Results from this Italian and Swiss study also support other pre-clinical studies taking place with human patients.
In a 2020 open-label study led by a research team at the University of Colorado, clinicians found that for 13 participants, CBD had beneficial effects on tremors, sleep, and both emotional and behavioral control.
However, at the high-dosages used in the open-label study, participants also experienced adverse side effects such as diarrhea, dizziness, and headaches, indicating that more research is needed to strike a balance between delivering a strong treatment outcome without introducing complications.
Different administration routes such as intravenous injections compared to taking CBD orally can alter the amount of drug that becomes available in the body, which in turn, affects its effectiveness.
How soon treatment is provided can have an impact as well.
“Current clinical studies administer CBD after a diagnosis is made,” the authors said. “[At which point] about 50% of the dopamine-producing neurons in the brain are already destroyed.”
While additional research is needed to fully understand how CBD can be an effective therapeutic option for Parkinson’s disease, it’s clear for the authors that “the results of this study overall support the therapeutic potential of [CBD] as a disease-modifying and symptomatic treatment.”
Calvin Chan is a researcher and medical writer from Edmonton, Canada. As a big science nerd, he loves reading and writing about everything science - from cannabis to dark matter and even alien life. Calvin has a PhD from the University of Alberta.