Studying the association between gut microbe and Parkinson’s disease

A new study by the University of Surrey suggests that Parkinson’s disease may begin in the gut and pass on to the brain.

The study discovered that almost 30% of gut bacteria with Parkinson’s disease vary from those that do not have the disease—which indicates a connection between the two. In the largest study as such, scientists from the University of Surrey and the University of Alabama at Birmingham examined the gut bacteria’s role in the progress of Parkinson’s disease—a disease in which some brain parts become gradually damaged over several years.

“Impairments and deaths due to Parkinson’s disease are increasing faster than any other neurological disorder worldwide, with diagnosed cases more than doubling in the last 25 years. This is very concerning as there is no known cure. However, the more we learn about the causes of the disease, the more informed we can be in developing new treatments and, eventually, a cure.”

Previous research in this field has indicated a possible link between gut bacteria and the disease; however, these studies have been small and used dated methodologies.”

Dr Ayse Demirkan, Study Co-Author and Senior Lecturer, AI Multiomics for Health and Wellbeing, University of Surrey

To examine a connection, 490 individuals with Parkinson’s disease and 234 neurologically healthy people were engaged. Every individual gave a stool sample and data about oneself, making the largest dataset of this type to date. A thorough analysis of their stool samples revealed that genes, bacteria, and biological pathways vary by over 30% in those with Parkinson’s when compared to those without the disease.

For instance, the bacterial species (Bifidobacterium dentium), which results in anaerobic infections like brain abscesses, were found to be raised seven-fold in individuals with Parkinson’s and the bacterial species such as Roseburia intestinalis, which is considered as the inhabitant of healthy colons (constipation is a known symptom of Parkinson’s), were found to have a 7.5-fold reduction.

Remarkably, scientists also found a cluster of bacteria (Klebsiella pneumonia, Escherichia coli, and Klebsiella quasipneumoniae), which are considered to result in infections, was increased in individuals with Parkinson’s.

“The make-up of the gut bacteria of those with Parkinson’s consists of an overabundance of pathogens and bacteria that may prompt immune responses among multiple other mechanisms involving various bacterial metabolic pathways, showing us a complex facade of the disorder in the gut.”

However, our current research is not designed to answer whether the bacteria itself is the initial cause of the disease, some may also be a consequence of the disease, or may be even influenced by the genetic makeup of the individual.”

Dr Ayse Demirkan, Study Co-Author and Senior Lecturer, AI Multiomics for Health and Wellbeing, University of Surrey