Scientists from University College London have revealed that changes in human gut bacteria may be an early warning sign of Parkinson's disease, years before the first symptoms appear.
Each person has a unique set of microbes living in their digestive system, including bacteria, fungi, and viruses. But researchers have found that people with Parkinson's disease have a distinctive composition of these microbes, and that the same is true for healthy people with a genetic predisposition to the disease.
These findings may help in developing tests that reveal a person's susceptibility to Parkinson's disease, and may also open the door to new methods of prevention by directly targeting the intestines.
Parkinson's disease is a leading cause of disability worldwide and the fastest-growing neurological disease in terms of both prevalence and mortality, according to Professor Anthony Shapiro, the study's lead researcher. He added that there is an urgent need for treatments that can halt or slow the disease's progression.
Shapiro explained that recent years have seen increasing recognition of the link between gut health and this brain disorder, and that their study strengthened the evidence and showed that gut microbes can be an early warning sign that precedes the onset of symptoms by years.
It is worth noting that researchers from King's College London had previously found a link between bacteria found in the mouth and intestines and the deterioration of mental abilities in Parkinson's patients, including the transition from simple memory problems to dementia, a common and distressing symptom of the disease.
According to the research paper published in the journal Nature Medicine, the researchers analyzed data from 271 people with Parkinson's disease, 43 people carrying a gene variant called GBA1 that increases the risk of developing the disease by up to 30 times, and these were asymptomatic, in addition to 150 healthy participants.
It was found that more than a quarter of the microbes in the guts of Parkinson's patients were different from those of healthy individuals, and this difference was even more pronounced among those in advanced stages of the disease. A similar difference was also observed in healthy individuals carrying the dangerous gene variant, even though they had not yet shown any symptoms.
Professor Shapiro said this discovery is the first of its kind to identify gut bacteria found in Parkinson's patients and also in people with a genetic predisposition before symptoms appear, opening the door not only to identifying those at risk, but also to finding out if changing these bacteria through dietary modifications or medication can reduce the likelihood of developing the disease.
The study participants also provided data on their dietary habits, and the results indicated that people who eat a balanced and varied diet are less likely to have a bacterial composition that suggests an increased risk of Parkinson's disease. However, further research is still needed to understand the other genetic and environmental factors that play a role in determining whether or not a person will develop the disease.
