Scientists have found a link between the use of oral antibiotics and the risk of Parkinson's disease. They suggest that the connection could be due to the drugs' impact on gut microbes.
The strongest links were for macrolides and lincosamides. Doctors prescribe oral dosages of these common antibiotics to fight a range of microbial infections.
A paper on the new study, by researchers at Helsinki University Hospital in Finland, appears in a recent issue of the journal Movement Disorders.
The discovery follows earlier research that found that people with Parkinson's disease often have altered gut microbes, for reasons that were unclear. In addition, the alterations often preceded the presentation of Parkinson's symptoms.
Those earlier studies found that changes in the gut that are typical in Parkinson's disease can occur 2 decades before diagnosis.
"The link between antibiotic exposure and Parkinson's disease fits the current view that in a significant proportion of patients the pathology of Parkinson's may originate in the gut, possibly related to microbial changes, years before the onset of typical Parkinson's motor symptoms," says senior study author Dr. Filip Scheperjans, a neurologist at Helsinki University Hospital.
"The discovery may also have implications for antibiotic prescribing practices in the future," he adds.
Parkinson's disease and the gut
Parkinson's is a condition that kills dopamine cells in the substantia nigra. This is a part of the brain that controls movement. This damage causes symptoms including stiffness, shaking, and problems with balance, all of which are common in Parkinson's.
People with Parkinson's disease may also develop other symptoms, such as depression, mood changes, sleep disruption, skin problems, constipation, and urinary difficulties.
The symptoms of Parkinson's usually take years to develop, and they can progress differently in different people.
According to the Parkinson Foundation, around 10 million people have Parkinson's disease worldwide. In the United States, health professionals are diagnosing it in around 60,000 people every year.
More and more studies are finding links between changes to gut microbes and brain conditions such as multiple sclerosis, autism, schizophrenia, depression, and Parkinson's disease.
However, there is still much debate about whether gut microbe changes actually cause these conditions or merely accompany them.
First study of antibiotics and Parkinson's
In their study paper, Dr. Scheperjans and colleagues note that researchers have observed gut microbe changes in early and established Parkinson's disease, and that antibiotics can have long-term impacts on microbe populations.
However, until their new study, nobody had actually investigated whether or not there was a direct link between antibiotic exposure and the risk of Parkinson's disease.
So, to address this gap, they carried out a case-control study using nationwide medical data from Finland.
From national registries, the team identified people who had received a diagnosis of Parkinson's disease during 1998–2014. They also used national databases to source individual purchases of oral antibiotics during 1993–2014.
They then applied statistical methods to these data to search for links between previous oral antibiotic exposure and Parkinson's disease.
The analysis compared antibiotic exposure in 13,976 people who received a diagnosis of Parkinson's disease with that of 40,697 controls who did not. It only compared people with Parkinson's with controls of the same sex, age, and residential location.
The team also categorized antibiotic exposure according to dosage, chemical composition, mechanism of action, and antimicrobial range.
Further studies need to confirm the findings
The results suggest that exposure to macrolides and lincosamides had the strongest links to Parkinson's disease risk.
The analysis also revealed links to a raised risk of Parkinson's disease for anti-anerobics and tetracyclines up to 15 years before diagnosis. There were also links for sulfonamides, trimethoprim, and antifungal drugs up to 5 years before diagnosis.
The researchers call for further investigations to confirm these findings.
If future studies come to the same conclusions, increased susceptibility to Parkinson's disease could join the list of potential hazards that doctors will need to consider when prescribing antibiotics.
"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."
Dr. Filip Scheperjans