cells

cells, called neurons of the brain (Alzheimer Disease.Org, 2017).
Changes in the Brain in Alzheimer’s Disease
Although they still do not know how to process Alzheimer’s disease begins, it seems likely that damage to the brain begins a decade or more before the problems become apparent. During the preclinical stage of Alzheimer’s disease, people are free of symptoms, but toxic changes are taking place in the brain. Abnormal deposits of proteins form the amyloid plaques and neurofibrillary tangles of tau in the brain, and once healthy for neurons begin to function with less efficiency. Over time, neurons lose their ability to function and communicate with each other, and eventually die.
In a short time, the damage extends to a nearby structure in the brain called the hippocampus, which is essential in the formation of memories. As more neurons die, the affected regions of the brain begin to decrease. By the final phase of Alzheimer’s, damage is widespread, and brain tissue has been significantly reduced.