A-beta or amyloid beta is a normal protein that you would find in all our brains, but in Alzheimer’s disease it mutates or changes. When plaques form in the brain, they damage nerve cells and these damaged nerve cells cannot regenerate and they die.
The other major microscopic change that occurs inside the brains of people with Alzheimer’s disease is the neurofibrillary tangle. The main protein composition of the tangle is again a changed form of a normal brain protein called tau. These tau tangles are impenetrable, so when the nerve cell dies, all that is left behind is this tau tangle which is sometimes referred to as a ‘ghost tangle’.