Reply to the Letter to the Editor "The Microbiota in Parkinson's Disease: Ranking the Risk of Heart Disease".

Although it is clear that disturbance of the gut microbiota also affects brain and heart function in Parkinson's disease patients, the changes in the gut microbiota reported so far do not explain why we consider variation in the gut microbiota to be an independent risk factor for sudden death. Further studies are needed to determine whether it causes sudden death in PD.