Researchers at the California Institute of Technology say their animal experiments have “transformed” their understanding of Parkinson’s, and that gut bacteria is likely to blame for the devastating brain disorder.

In order to come to their conclusion, scientists produced mice who were genetically prone to developing Parkinson’s. These altered mice produce high levels of the protein the protein alpha-synuclein, which is present in patients with the disease.

But, during their experiment, the team noticed something curious: only those mice with certain bacteria in their stomachs developed Parkinson’s. The mice prone to Parkinson’s who lacked the gut bacteria did not go on to develop the disease.

Dr. Timothy Sampson, who worked on the study, stated:

“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.”

Scientists confirmed their theory by swapping gut bacteria in mice prone to the disease. Giving the mice gut microbiota from individuals who suffered from Parkinson’s led to the animals developing symptoms, while transplanting gut microbiota of healthy people to the mice alleviated the problem.

The mice without the offending gut bacteria still overproduced alpha-synuclein, but they did not develop symptoms to the same level, or at all, in comparison to those with the gut bacteria in their systems. They also outperformed the mice with Parkinson’s related gut bacteria on a series of motor skill tests that were meant to mimic those given to humans with Parkinson’s disease.

Researchers concluded that whether or not bacteria was present was not the issue, but the type of bacteria that exists in the gut. In the next phase of the study, they will begin to identify specific microbiota that cause Parkinson’s and try to find ways to eradicate it from the body.

Sarkis Mazmanian, one of the researchers on the team, stated:

“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.”

The team’s research was published this week in the scientific journal Cell.


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