Dementia is caused by damage to brain cells which interferes with their ability to communicate with each other.
Part 1: Brain atrophy - the loss of brain cells called neurons - is widespread in the later stages of Alzheimer’s disease.
Part 2: In a brain with Alzheimer’s, abnormal levels of beta amyloid plaque clump together and collect between neurons. There are also abnormal accumulations of a protein called tau that collect inside neurons to form neurofibrillary tangles.
Part 3: There is some evidence that inflammatory processes in the brain result in increased damage to the myelin sheath.