A stomach bug that causes ulcers may help to trigger Parkinson's disease, research suggests.
Mice infected with one strain of Helicobacter pylori bacteria went on to develop Parkinson's-like symptoms within five months, scientists found.
"Our findings suggest that H. pylori infection could play a significant role in the development of Parkinson's disease in humans," said Dr Traci Testerman, from Louisiana State University in the US.
An association between stomach ulcers and Parkinson's disease has been recorded as far back as the 1960s. At that time it was not even known that H. pylori was responsible for ulcers.
More recently, a number of studies have shown that people with Parkinson's are more likely to be infected with the bacterium.
Dr Testerman's team infected young and aged mice with three different strains of H. pylori and observed their movement ability and levels of the brain chemical dopamine.
One particular strain led to significant deterioration of both.
"The results were far more dramatic in aged mice than in young mice, demonstrating that normal ageing increases susceptibility to Parkinsonian changes in mice, as seen in humans," said Dr Testerman, who presented the findings today at the American Society for Microbiology's annual meeting in New Orleans.