Alzheimer’s disease in human beings is characterised by the degeneration of:

Alzheimer's is a progressing brain disease where nerve cells progressively die and shrink. Abnormal protein clumping in the brain causes the disease. Clumps of amyloid protein build up between brain cells, disrupting communication, and clumps of tau protein tangle within brain cells. Without these brain cells, communication networks in the brain unravel, leading to the characteristic symptoms of Alzheimer disease: trouble remembering, declining thinking abilities, and emotional or personality changes.