Figure 1.

Proposed common underlying mechanisms between rosacea and various neurological disorders. Activation of transient receptor potential vanilloid type 1 (TRPV) receptors in neuronal tissues and skin induces the release of neuropeptides such as calcitonin gene-related peptide (CGRP) and substance P in patients with rosacea and migraine. These neuropeptides induce the vasodilation of cutaneous blood vessels and degranulation of mast cells, further stimulating the release of inflammatory molecules and matrix metalloproteinases (MMPs) in rosacea. In Parkinson’s disease and Alzheimer’s disease, the increased expression of MMPs is also observed in the neural tissue, cerebrospinal fluid, and serum of patients, which disrupts the blood–brain barrier and further induces neuroinflammation. Genetic polymorphisms in the TACR3 gene are found in patients with rosacea and Parkinson’s disease. This shared pathogenic link might synergistically influence the association between neurologic disorders and rosacea.