Link found between stomach infection and Parkinson’s symptoms

Parkinson's disease is the world's second most common neurodegenerative disorder, causing tremors and decreasing motor coordination. Causes are elusive and doctors currently can only treat its symptoms.

Researchers at the University of Malaya analysed a small group of Parkinson's disease patients with and without a common infection of the stomach lining caused by the bacterium Helicobacter pylori. Their results showed that those with the infection -- about a third of the total -- tested worse in motor problems related to Parkinson's disease.

Subjects whose infection could be treated and eradicated showed fewer Parkinson's disease symptoms in motor performance tests, while those who stayed infected had further declines in their test results.

More than half of the world's population carries H. pylori, with the highest infection rates in Asian countries. It affects mucous membranes in the gut and causes chronic infections, often contracted during childhood. The bacterium can cause a range of digestive tract disorders and can linger indefinitely unless treated, although some subjects show few symptoms.

The researchers propose two main theories to explain their results. The first is that the infection may reduce the uptake of levodopa, a drug that reduces symptoms of Parkinson's disease. More speculatively, chronic H. pylori infections might aggravate or even trigger Parkinson's disease. However, they also speculate that it's possible that Parkinson's disease may make subjects more prone to contracting the infection.

The researchers say their limited study of 103 subjects aimed mainly to confirm the link between Helicobacter pylori infection and Parkinson's disease suggested by previous, less rigorous research. In addition to its size, the study was limited by the fact that it took place in a single Malaysian clinic and that it was cross-sectional; so it was essentially a data snapshot taken at a certain place and time.

But they say the link they found between the infection and worsened symptoms of Parkinson's disease is strong enough to justify further, larger, well-designed clinical trials to confirm it and investigate its causes in more depth.