Is a neurogenerative disorder that is the most common form of dementia, a general term for loss of memory and other intellectual abilities serious enough to interfere with daily life. is distinguished by the loss of nerve cells and synapses in the cerebral cortex and subcortical regions of the brain as well as the appearance of plaques and tangles, which make this disease unique. is an irreversible, progressive brain disease that slowly destroy memory, reasoning, judgment, communication, and the ability to carry out simple tasks and activities of daily living.