Gut bacteria linked to the development of Parkinson’s disease

A recent study suggests that Parkinson’s disease, in which parts of the brain are gradually damaged over many years, may actually start in the gut.

Almost 30% of gut bacteria in patients with Parkinson’s disease differed from those without, according to the study by British and American researchers.

Study co-author Ayse Demirkan, a senior lecturer at the University of Surrey, noted that death and disability from Parkinson’s disease is increasing faster than any other neurological disorder in the world. Diagnosed cases have more than doubled over the past 25 years.

“This is very concerning because there is no known cure,” Demirkan said in a university press release. “However, the more we learn about the causes of the disease, the more information we can have to develop new treatments and, eventually, a cure.”

Parkinson’s disease is a brain disorder that can cause uncontrollable movements such as shaking, stiffness in limbs, and difficulty with balance and coordination.

Previous research had pointed to a possible link between gut bacteria and disease, Demirkan said, though those studies were small.

This study recruited 490 people with Parkinson’s disease and 234 neurologically healthy people. Each provided a stool sample and information about themselves.

When samples were analyzed, the researchers found that bacteria, genes and biological pathways differed by more than 30% in people with Parkinson’s disease compared to those without the movement disorder.

An example was the bacterial species Bifidobacterium dentium, which is known to cause infections such as brain abscesses. They were seven times higher in people with Parkinson’s disease, while levels of Roseburia intestinalis, a bacteria found in the healthy colon, were 7.5 times lower. Constipation is a recognized symptom of Parkinson’s disease.

A group of bacteria known to cause infections – Escherichia coli, Klebsiella pneumonia and Klebsiella quasipneumoniae – were elevated in people with Parkinson’s disease.

“Our current research is not designed to determine whether the bacteria itself is the initial cause of the disease, some may also be a consequence of the disease, or may even be influenced by the genetic make-up of the individual,” Demirkan said.

The results were published in Nature Communications.

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