Early Parkinson’s warning signs may be hiding in the gut, study finds

Specific bacteria in the gut could predict a person’s risk of developing Parkinson’s disease years before symptoms appear, new research suggests.

Led by researchers from University College London (UCL), an observational study analyzed the gut microbes of 271 patients in the U.K. who had been diagnosed with Parkinson’s.

Also included in the study were 43 carriers of the GBA1 variant, which has been linked to an almost 30 times higher risk of Parkinson’s disease. These participants did not have symptoms of the disease. There was also a control group of 150 healthy participants without the gene.

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Based on fecal samples, more than one-quarter of gut microbes — bacteria and other microorganisms in the digestive tract — were in different amounts for people with Parkinson’s disease compared to healthy individuals, according to a press release.

Non-symptomatic people carrying the Parkinson’s gene also had microbial changes that resembled an "intermediate" stage of the disease, which suggests that microbial changes may happen prior to symptoms emerging.

Those who reported eating a more diverse and balanced diet were less likely to have microbiome patterns associated with higher Parkinson’s risk, the researchers found.

The findings, which were published in Nature Medicine, were also seen in over 1,400 participants across the U.K., Korea and Turkey, suggesting that the microbial changes are consistent across different cultures and dietary patterns.

"Parkinson’s disease is a major cause of disability worldwide, and the fastest growing neurodegenerative disease in terms of prevalence and mortality," lead author Professor Anthony Schapira of the UCL Queen Square Institute of Neurology said in the release.  

"There is an urgent need to develop treatments that can stop or slow the disease’s progression."

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Patients with Parkinson's are known to have "significant gut abnormalities," according to Dr. Earnest Lee Murray, a board-certified neurologist at Jackson-Madison County General Hospital in Jackson, Tennessee.

One of those is severe constipation, which can occur several years before tremors and other symptoms. 

"There has long been a theory about the gut-brain axis and whether or not the pathology for Parkinson's starts in the gut decades before stereotypical features are noted," Murray, who was not involved in the research, told Fox News Digital.

The neurologist said the study sets the stage for additional research exploring the gut-brain axis theory, which could determine whether early pre-symptomatic treatments could prevent or mitigate the risk of developing Parkinson's later in life.

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"With an aging population that is living longer, the prevalence of Parkinson's is increasing significantly, which underscores the importance of studies like this that attempt to prevent this debilitating neurodegenerative disease," Murray added.

Dr. Aaron Ellenbogen, medical director of the Parkinson’s Disease & Movement Disorders Center at the Michigan Institute for Neurological Disorders, said it is not surprising that a change in the organisms living in the GI tract can be a signature of evolving Parkinson's pathology.

"In general, people with GBA mutations tend to have Parkinson's symptoms evolve in a way that is more consistent with a gut-first presentation," Ellenbogen, who also was not involved in the study, told Fox News Digital.  

Others may experience a different set of symptoms, including loss of sense of smell, before developing signs of motor Parkinson's disease, he noted.

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"In fact, many of these people don't develop the symptoms of constipation and REM behavior disorder until later in their disease course," Ellenbogen said. "These people may actually have a form of Parkinson's that starts in the brain."

There were some limitations to the study, the researchers acknowledged. Because it was observational in design, it could not prove that the microbiome changes directly caused Parkinson’s.

The researchers also noted that not everyone with at-risk microbiome profiles will develop the disease, as other genetic or environmental factors could play a role.

Additionally, differences in microbiomes across various populations could skew the results.

"To enable both the research and eventual use of such treatments, we need to develop the means for very early detection of people who will, or likely will, go on to develop the disease," Schapira said.

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The study was funded by the Michael J. Fox Foundation for Parkinson’s Research and the UK Medical Research Council.

Fox News Digital reached out to the researchers for comment.