Parkinson’s disease: the walls are closing in on Desulfovibrio bacteria

What do Pope John Paul II, actor Michael J. Fox (Marty McFly in Back to the Future) and boxer Muhammad Ali have in common? All have been affected by Parkinson’s disease, a degenerative brain disorder characterized by tremors. However, like the nearly 9 million people worldwide affected by the disease, these celebrities also have in common a bacterium called Desulfovibrio. Or to be more precise, an excess of this bacterium, which is thought to be present in (too?) large quantities in Parkinson’s sufferers, particularly those with severe forms of the disease.

From bacteria to brain aggregates

Are these bacteria responsible for the disease? Yes, according to the results of a Finnish study published in 2023. Their work involved experiments on nematodes – round, slender worms – and, more specifically, worms called C. elegans, which were fed Desulfovibrio bacteria extracted from the stools of Parkinson’s patients or their healthy spouses. The researchers found that the worms fed Desulfovibrio bacteria from the Parkinson’s patients developed protein aggregates in the brain typical of the disease that were greater in number and size when compared to worms fed the same bacteria from the spouses’ stools. In other words, strains of Desulfovibrio bacteria, particularly those from Parkinson’s patients, promote the accumulation of aggregates.

Increased mortality

Furthermore, worms fed with Desulfovibrio bacteria from Parkinson’s patients were more likely to die after four days. This excess mortality may be explained by the greater virulence of the bacteria taken from Parkinson’s patients.

This discovery raises enormous hopes of finding a way to identify Parkinson’s patients by tracking the bacteria in their stools, but also of one day being able to slow down or even prevent the disease by eradicating these pathogenic bacteria or simply limiting their number.