Lumpy Proteins Stiffen Blood Vessels of the Brain

A study in Proceedings of the National Academy of Sciences found lumpy deposits of a protein called Medin, which arise in virtually all older adults, reduce blood vessel elasticity during aging and may raise the risk of vascular dementia, reports ScienceDaily . Medin is mainly found in the aorta and in blood vessels, but the researchers also detected Medin particles in postmortem human brain tissue samples and in old mice. The mice experiments also revealed that when the brain is active and a higher blood supply is needed, vessels with Medin deposits expand more slowly than those without Medin. "Brain vessels with Medin appear to be less flexible and therefore react more sluggishly," said Jonas Neher at the German Center for Neurodegenerative Diseases. The ability of the vessels to rapidly expand is critical for regulating blood flow and supplying the brain with sufficient oxygen and nutrients. "If this ability is impaired, it can have far-reaching consequences for the functioning of organs" said Neher, implying that Medin deposits contribute to the deterioration of blood vessel function as one ages. He has theorized that "fibers run in the vessel wall that allow the blood vessel to stretch and contract. Since the protein deposits are embedded in the vessel wall, they may interfere with the function of these elastic fibers."