From the NIH: Impaired clearance, not overproduction of toxic proteins, may underlie Alzheimer’s disease 09 December 2010 In Alzheimer's disease, a protein fragment called beta-amyloid accumulates at abnormally high levels in the brain. Now researchers funded by the National Institutes of Health have found that in the most common, late-onset form of Alzheimer’s disease, beta-amyloid is produced in the brain at a normal rate but is not cleared, or removed from the brain, efficiently. In addition to improving the understanding of what pathways are most important in development of Alzheimer's pathology, these findings may one day lead to improved biomarker measures for early diagnosis as well as a new approach to treating this devastating disorder. Many believe that accumulation of abnormal levels of beta-amyloid in the brain initiates a cascade of events leading to the death of brain cells and ultimately to dementia. In the rare, early-onset forms of Alzheimer's that are link...