Preclinical signs of Parkinson's disease: A possible association of Parkinson's disease with skin and hair features.

Parkinson's disease (PD) is a neurodegenerative disorder, characterized by loss of dopaminergic neuromelanin containing neurons in the substantia nigra. Peripheral melanin, found in skin and hair, and neuromelanin appear to have some characteristics in common and share the same precursor for their synthesis; therefore, skin and hair features could be associated with PD. We hypothesize that earlier age at onset of hair greying, greater tendency to sunburn, difficulty tanning and dysregulation of sebum production are more common among PD patients due to genetically determined lower constitutive amounts of melanin and accumulation of α-synuclein in the skin, which leads to disrupted synthesis of peripheral melanin and dysregulated sebum secretion.