The formation of amyloid plaques and neurofibrillary tangles are thought to contribute to the degradation of the neurons (nerve cells) in the brain and the subsequent symptoms of Alzheimer’s disease.
AMYLOID PLAQUES
One of the hallmarks of Alzheimer’s disease is the accumulation of amyloid plaques between nerve cells (neurons) in the brain. Amyloid is a general term for protein fragments that the body produces normally. Beta-amyloid is a fragment of a protein that is snipped from another protein called amyloid precursor protein (APP). In a healthy brain, these protein fragments would be broken down and eliminated. In Alzheimer’s disease, the fragments accumulate to form hard, insoluble plaques.
NEUROFIBRILLARY TANGLES
Neurofibrillary tangles consist of insoluble twisted fibers that are found inside of the brain’s cells. They primarily consist of a protein called tau, which forms part of a structure called a microtubule. The microtubule helps transport nutrients and other important substances from one part of the nerve cell to another. In Alzheimer’s disease, however, the tau protein is abnormal and the microtubule structures collapse.