Alzheimer's brain. Computer graphic of a vertical (coronal) slice through the brain of an Alzheimer patient (at left) compared with a normal brain (at right). The Alzheimer's disease brain (red) is considerably shrunken, due to the degeneration and death of nerve cells. Apart from a decrease in brain volume, the surface of the brain is often more deeply folded. Tangled protein filaments (neurofibrillary tangles) occur within nerve cells and patients also develop brain lesions of beta- amyloid protein. Alzheimer's disease accounts for most cases of senile dementia. Symptoms include memory loss, disorientation, personality change and delusion. It ultimately leads to death. .