It is suspected that Parkinson's disease can start both within the brain and elsewhere in the body. A recent Danish study shows that it usually starts either one or the other, so the disease does not typically begin simultaneously within and outside the brain. This strengthens the suspicion that it may be possible to distinguish different types of the disease: 'brain first' and 'body first'. The article below provides an overview of what is currently known.
Jacob Horsager en Per Borghammer, 2024. Brain-first vs. body-first Parkinson's disease: An update on recent evidence. Parkinsonism & Related Disorders, 106101. sciencedirect.com/science/a...