Alzheimer's disease. Coloured light micrograph of brain tissue from an Alzheimer's disease sufferer. Both of the classic pathological features of this disease are seen here. At lower right is a plaque (yellow/black) containing the abnormal protein amyloid. Also seen are several neurofibrillary tangles (smaller yellow areas), thickened parts of the cytoplasm of nerve cells. Both of these abnormalities disrupt the normal working of the brain. The symptoms of Alzheimer's disease include memory loss (particularly of recent events), disorientation and mood changes. Death occurs after several years of decline, and there is no cure. Magnification: x50 at 6x7cm size.