Alzheimer's and Slow Garbage Removal
Recent research into the causes of Alzheimer's disease: "Do rising brain levels of a plaque-forming substance mean patients are making more of it or that they can no longer clear it from their brains as effectively? ... Clearance is impaired in Alzheimer's disease. We compared a group of 12 patients with early Alzheimer's disease to 12 age-matched and cognitively normal subjects. Both groups produced amyloid-beta (a-beta) at the same average rate, but there's an average drop of about 30 percent in the clearance rates of the group with Alzheimer's. ... Scientists calculate this week [that] it would take 10 years for this decrease in clearance to cause a build-up of a-beta equal to those seen in the brains of Alzheimer's patients. The results have important implications for both diagnosis and treatment. ... Scientists are now interested in learning how a-beta, a byproduct of normal metabolism, is moved out of the brain for breakdown and disposal. As these details come in, they will be essential for physicians working to diagnose the disease before symptoms develop and for drug developers, who can target the problems with pharmaceuticals. A-beta was recognized long ago as a key component of the brain plaques found during autopsies of Alzheimer's patients. One of the ways the brain clears away the a-beta normally produced by brain cell activity is by moving it to the spinal fluid for disposal. Studies have suggested that a drop in spinal fluid levels of a-beta may be a presymptomatic indicator of Alzheimer's disease, possibly because a-beta is getting stuck in the brain and starting to accumulate there." You might also look back at research into the functional decline of the choroid plexus in connection with Alzheimer's: it is a biological filtration system, and its progressive failure may be the cause of lower rates of clearance.
Link: http://www.eurekalert.org/pub_releases/2010-12/wuso-apc120710.php