EDN1 and early-onset autosomal dominant Alzheimer disease: ,53 Elevated levels of endothelin-1 (EDN1) in Alzheimer’s disease may contribute to cerebral hypoperfusion via contraction of smooth muscle cells on penetrating arteries and arterioles24 and pericyte dysfunction, an essential component of the neurovascular unit, contributes to blood flow dysregulation and as mentioned, blood–brain barrier breakdown.