Figure 3

Differential contribution of vessel wall thickening (dark-brown coloration) to disease. (A) Atherosclerosis is a chronic inflammatory condition characterized by the accumulation of cholesterol-laden macrophages (foam cells) in arterial walls, partial occlusion and, when the plaques rupture, risk of myocardial infarction and stroke. Partial occlusion compromises oxygen supply to other tissues. (B) In Alzheimer disease neuronal loss is accompanied by thickening of brain vessel walls, recruitment of macrophages, and the formation of amyloid deposits of Aβ in the vicinity of the cerebrovasculature. Macrophages are implicated in shuttling Aβ between amyloid deposits and vessel walls. Mechanisms underlying neuronal loss are not understood, but impaired trans-vessel oxygen and glucose delivery, and reduced removal of toxic metabolites, may predispose to neuronal death; impairment of blood–brain barrier function may also contribute.