New Parkinson’s Disease Study Says Gut Bacteria May Be The Cause

Parkinson’s disease may be a serious brain disorder, but its roots may actually lie in gut bacteria, according to a new study published this week in the journal Cell.

As explained in a report from CNBC, Parkinson’s disease is a neurodegenerative disorder characterized by the buildup of the protein alpha-synuclein in the brain cells, which leads to the death of the cells. As the disease progresses, the classical symptoms begin to manifest – tremors, shakes, a loss of motor function, and other physical and mental symptoms. The disease is the second most common neurodegenerative disorder behind Alzheimer’s, affecting about 1 million Americans and 10 million people globally.

Earlier studies had suggested that Parkinson’s disease is very seldom hereditary in nature; environmental variables tend to be the main driving factors that determine one’s chances of acquiring the disease.


A multinational team of researchers from the United States and Europe performed experiments on mice, changing the features of their gut bacteria and effectively changing how Parkinson’s disease and its symptoms affect them. More interestingly, CNBC notes that this also applies to bacteria from humans suffering from the disorder, meaning the best course of Parkinson’s disease treatment may include a focus on the gut, instead of the obvious route of focusing on the brain. The new data, said researcher and California Institute of Technology professor of microbiology Sarkis Mazmanian, could be used in the creation of “next generation” probiotics that improve on existing treatments.

“One can imagine one day, maybe in our lifetimes, patients will be prescribed drugs, and in the pills will be the bacteria that protect them from disease or even maybe treat their disease symptoms.”

A report from the BBC explained how the researchers performed their experiments on animals, working on mice genetically engineered to develop Parkinson’s, with “very high” production levels of the protein alpha-synuclein. Based on their findings, it was only the mice with gut bacteria that developed symptoms, with the sterile mice not suffering from any adverse effects. Subsequent tests had lent more credence to the idea that gut bacteria may cause Parkinson’s, as transplanting bacteria from human patients to the mice resulted in more symptoms, as opposed to bacteria from people not suffering from the disease.

According to Caltech researcher Timothy Sampson, this was the big moment where he and his colleagues had linked gut bacteria to the development of Parkinson’s disease.

“This was the ‘eureka’ moment, the mice were genetically identical, the only difference was the presence or absence of gut microbiota. Now we were quite confident that gut bacteria regulate, and are even required for, the symptoms of Parkinson’s disease.”

Mazmanian was also quoted in the BBC report as saying his team’s discovery represents a “paradigm shift,” one that could lead to “entirely new possibilities” for human patients suffering from the disease. All told, the research could mean Parkinson’s doesn’t develop exclusively in the brain and that its origins may have been in the gut all along. The disease, however, still does not have any known cure.

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The findings have yet to be replicated and confirmed in humans, but reactions to the new study have been positive, showing hope that working on the gut may be much more effective than working on the brain when it comes to curing Parkinson’s.

Parkinson’s U.K. spokesman Dr. Arthur Roach, who was not involved in the study, told the BBC that there are many questions still unanswered regarding Parkinson’s disease treatment for humans, but acknowledged that the new study could spur on further research on treatment options.

“In recent years, evidence has been growing that Parkinson’s may begin in the gut, but the chain of events involved has so far remained a mystery. This work opens an exciting new avenue of study on the gut-brain connection in Parkinson’s.”

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