Higher exposure to commonly used oral antibiotics is linked to an increased risk of Parkinson's disease, according to a study which suggests the neurodegenerative disorder may be tied to the loss of beneficial gut bacteria.
The researchers, including those from the University of Helsinki in Finland, analysed the data of nearly 14,000 Parkinson's disease patients extracted from national registries during the years 1998-2014.
They compared the data with those from 40,697 non-affected persons matched for age, sex and place of residence in a case controlled manner.
The findings of the study, published in the journal Movement Disorders, revealed that the use of certain antibiotics can predispose people to Parkinson's disease with a delay of up to 10 to 15 years.
The researchers examined antibiotic exposure in the patients over three different time periods -- one to five, five to ten, and ten to fifteen years -- prior to the index date, based on drug purchase data.
They classified exposure to the drugs based on the number of purchased courses.
The scientists also examined drug exposure by classifying antibiotics according to their chemical structure, antimicrobial spectrum, and mechanism of action.
"Our results suggest that some commonly used antibiotics, which are known to strongly influence the gut microbiota, could be a predisposing factor," said study lead researcher Filip Scheperjans from Helsinki University Hospital.
He said the link between antibiotic exposure and Parkinson's disease fits the current view that in many patients the pathology of the disease may originate in the gut.
Scheperjans explained this may be related to microbial changes in the gut years before the onset of neurodegenerative symptoms like slowness, muscle stiffness, and shaking of the extremities.
The researchers said pathological changes typical of Parkinson's disease have been observed up to 20 years before patients get their diagnosis.
They added that constipation, irritable bowel syndrome, and inflammatory bowel disease have all been associated with a higher risk of developing Parkinson's.
"The discovery may also have implications for antibiotic prescribing practices in the future. In addition to the problem of antibiotic resistance, antimicrobial prescribing should also take into account their potentially long-lasting effects on the gut microbiome and the development of certain diseases," said Scheperjans.