Researchers at EPFL (Lausanne) and Amsterdam UMC examined tiny nerve bundles in skin samples taken from the necks of 46 people who had donated their bodies to science. The donors fell into four groups: confirmed Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and people with no neurological disease. All three diseases are called synucleinopathies — conditions where the protein alpha-synuclein misfolds and accumulates abnormally. Using electron microscopy (a technique that can image structures far too small for a regular microscope), the team examined more than 1,100 individual myelin sheaths — the fatty insulating wrapping around nerve fibers, similar to the plastic coating on an electrical wire. They scored each sheath for signs of damage: fragmentation and abnormal swellings.
The key finding was that the PD group showed measurably higher myelin damage in these skin nerves than the MSA group and the healthy control group. This is a post-mortem human tissue study — all samples came from donors who had already died and had their diagnoses confirmed by brain autopsy. That is an important limitation: it tells us that the damage is present in PD but does not yet show when it appears during the disease, whether it could be detected reliably in a living patient's skin biopsy, or whether the degree of damage tracks with how severe symptoms were.
For people living with Parkinson's, the practical implication is still distant but real: accurately telling PD apart from MSA or DLB is genuinely difficult, especially early on, because the diseases can look similar. If a simple skin biopsy could one day reveal a characteristic myelin damage signature, it might aid diagnosis or help researchers select the right patients for clinical trials. Skin is far more accessible than brain tissue or cerebrospinal fluid. The researchers describe peripheral nerve myelin analysis as a potential future classifier for synuclein diseases — but validating that in living patients, with larger numbers and prospective study designs, is the necessary next step. Clinical use is realistically years away.