The Journal of Neuroscience recently featured a debate over the hypothesis that Parkinson's disease is, at least in some cases, caused by prions – misfolded proteins that spread from neuron to neuron.

A prion is a protein that has taken on an abnormal shape and that can spread itself by making other, healthy molecules of the same protein adopt its abnormal configuration. The best-known prion disease is variant CJD aka “mad cow disease”, but some researchers believe that Parkinson's is also a prion disorder.