Researchers how produced evidence suggesting that reduced blood flow to the brain prevents amyloid beta from being carried away, thereby worsening the progression of Alzheimer's - which explains why exercise seems to help resist this age-related condition. Here is a different view of why reduced blood flow is bad, and a reminder that Alzheimer's a complex, many-faceted degeneration: "when the brain doesn't get enough sugar glucose - as might occur when cardiovascular disease restricts blood flow in arteries to the brain - a process is launched that ultimately produces the sticky clumps of protein that appear to be a cause of Alzheimer's. [Researchers] discovered a key brain protein is altered when the brain has a deficient supply of energy. The altered protein, called elF2alpha, increases the production of an enzyme that, in turn, flips a switch to produce the sticky protein clumps. ... What we are talking about here is a slow, insidious process over many years where people have a low level of cardiovascular disease or atherosclerosis in the brain. It's so mild, they don't even notice it, but it has an effect over time because it's producing a chronic reduction in the blood flow."

Link: http://www.eurekalert.org/pub_releases/2008-12/nu-bsa122308.php