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– Progressive reduction in intraepidermal nerve fiber density (IENFD) parallels worsening cognitive impairment in Parkinson disease (PD).
– Lower IENFD correlates with frontal and insular gray matter atrophy, regions linked to cognitive functions.
– Skin denervation independently predicts cognitive impairment severity and distinguishes PD cognitive subtypes with good diagnostic accuracy.
– Brain atrophy statistically mediates the relationship between peripheral small fiber loss and cognitive deficits, supporting a peripheral-central neurodegenerative axis in PD.
