Mechanism of Alzheimer's Disease

the mysteries and paths of alzheimer's disease subjective memory complaints and a decline of performance of daily activities may indicate early stages of alzheimer's disease or a.d particularly in patients age 65 or older ad is a progressive disease beginning with pathological changes that occur decades before clinical symptoms leading eventually to the development of mild

cognitive impairment functional symptoms and then dementia ad accounts for as many as 80 percent of all dementia diagnoses today we are able to diagnose ad in its early symptomatic stages by assessing biomarkers and by using tests to evaluate cognitive performance functional impairment and behavioral symptoms to better understand the disease we must look back in time to the pathological

origins of a.d within the brain the two pathological hallmarks of ad appear at distinct locations within the brain plaques made up of a beta occur outside of neurons while neurofibrillary tangles composed of tau protein develop within neurons abnormal accumulation of a beta within the brain may begin decades before symptoms appear amyloid beta is produced when amyloid

precursor protein or app is cleaved by beta secretase base 1 and then by gamma secretase a beta is formed in the course of normal brain metabolism however it may be over produced in certain individuals in healthy people a beta is cleared from the brain through systemic circulation and local processes such as uptake by

microglia both the overproduction of a beta and inadequate clearance mechanisms can cause a beta peptides to accumulate in the brain and self-aggregate into plaques plaque deposition is first seen in the brain's neocortex the center of higher mental functions it progresses to the more primitive cortex including the hippocampus and related structures involved in learning and memory