Alzheimer's disease is defined by the National Institutes of Health (NIH) as a degenerative brain disease. Most patients start exhibiting symptoms after they reach the age of 60. Alzheimer's disease affects the brain through exponentially greater cell death and tissue loss, resulting in a decreased brain size. As a result, behavior, memory and thinking are affected. The effects of Alzheimer's disease on the patient's brain can be seen via a brain scan and microscopic examination of brain tissue.
Brain Shrinkage
The Alzheimer's Association notes that the two areas affected by the brain shrinkage are the cortex and the ventricles. The cortex is the largest part of the brain: It is divided into two hemispheres and four lobes on each hemisphere (frontal lobe, parietal lobe, temporal lobe and occipital lobe). The cortex is also responsible for multiple function, such as remembering, thinking and planning. As a result of Alzheimer's disease, the patient's cortex shrinks dramatically. A part of the cortex responsible for converting short-term memories into long-term memories, the hippocampus, is severely affected. Ventricles, on the other hand, grow larger as a result of Alzheimer's disease, according to the Alzheimer's Association. This creates larger gaps in the brain and decreases the overall brain mass.
Plaque Formation
Damage to the brain can also occur on the microscopic level, as pointed out by the NIH. One type of damage found is plaques, which are proteins that collect between nerve cells and create clusters; these plaques are not found in the brains of healthy individuals. The plaques are formed when beta-amyloid, a type of protein, group together. Even in small formations, beta-amyloid can be damaging: plaques can interfere with communication between the brain cells, resulting in inflammation, according to the Alzheimer's Association.
Tangle Formation
Another effect Alzheimer's disease has on the brain is the formation of tangles, which the Alzheimer's Association states is collapsed protein that wraps around dying cells. The progression of Alzheimer's disease destroys the cell transportation made up of another type of protein, tau. The tau protein then collapses, forming the tangles. As a result, nutrients cannot be exchanged through the cell transportation, causing brain cell death.
