Gut Microbiome Changes Linked to Parkinson’s Disease Risk

Alterations in gut microbes could help identify individuals at a higher risk for Parkinson’s disease even before any symptoms appear, a recent study suggests, and it opens the door for potential new treatments.

Researchers found distinct changes in the gut microbiome that were more evident in people with a genetic predisposition to Parkinson’s, and even more pronounced in those already diagnosed with the condition.

This finding could aid doctors in recognizing at-risk patients years before they show obvious symptoms. It also hints that adopting healthier eating habits or therapies that modify the microbiome could help delay or prevent the disease.

Professor Anthony Schapira, who leads the clinical and movement neurosciences department at University College London and spearheads the research, mentioned that this is the first instance of observing a microbial signature in people genetically predisposed to Parkinson’s who haven’t yet presented symptoms. The microbial signature seems to intensify as the disease advances.

“Interestingly, we also see these changes in a small section of the general population, possibly indicating an elevated risk,” Schapira noted.

The incidence of Parkinson’s has doubled over the last quarter-century, with over 8.5 million individuals currently living with the disease worldwide. This condition leads to progressive brain damage, resulting in tremors, slow motion, and stiffness in muscles. Additionally, many patients deal with depression, anxiety, memory issues, and balance problems.

Parkinson’s is a result of neuron loss in a specific brain area known as the substantia nigra. This loss reduces dopamine levels, which plays a role in many symptoms of the disease. Although there’s no cure, medications can enhance dopamine levels, and physiotherapy or surgery might also assist.

The research team at UCL examined clinical and fecal data from 271 patients with Parkinson’s, 43 individuals carrying the risk gene but without symptoms, and 150 healthy individuals.

Notably, more than a quarter of the gut microbes—176 species—showed differences between those with Parkinson’s and the healthy group, and these variations weren’t influenced by medication. A similar trend was noticed in those genetically vulnerable to the disease who still showed no symptoms.

They further validated their findings using additional medical data from 638 Parkinson’s patients and 319 healthy individuals from the UK, South Korea, and Turkey. A small fraction of healthy participants exhibited the microbiome signature, indicating possible risk for Parkinson’s, as noted in Nature Medicine.

The link between the microbial signature and Parkinson’s remains uncertain. It’s unclear whether the microbiome changes lead to the disease, the disease affects the microbiome, or if both factors influence one another. However, Schapira mentioned that microbiome changes might impact the production of a protein called alpha-synuclein, which is crucial in damaging neurons affected by the disease.

“Some bacteria can induce inflammation in the gut wall, resulting in increased levels of alpha-synuclein. This protein travels via the vagus nerve from the gut to the brain, reaching the brain cells impacted in Parkinson’s,” he elaborated. The vagus nerve serves as a communication link between the brain and major organs.

More research and clinical trials are essential to decipher how gut microbes relate to Parkinson’s and if altering the microbiome could provide protection against the disease. However, changes in diet might be beneficial. In this study, individuals with abnormal microbiome signatures tended to consume more processed foods and saturated fats instead of fruits, vegetables, fiber, fish, and lentils.

Claire Bale, an associate director of research at Parkinson’s UK, commented that this research adds to the mounting evidence of the microbiome’s significance in Parkinson’s. “The results indicate that fluctuations in the microbiome could start in the very early phases of the condition, with the degree of these changes potentially aligning with disease progression,” she stated.

“In recent years, we have recognized the benefits of physical activity on symptom management and possibly slowing down the disease’s progression. Our expanding knowledge of the gut microbiome brings similar promise that dietary adjustments could positively impact those living with Parkinson’s.”