Alzheimer's disease. Coloured light micrograph of tissue from the frontal cortex of the brain of an Alzheimer's disease sufferer. One of the classic pathological features of this disease can be seen here. The red areas are neurofibrillary tangles, thickened parts of the cytoplasm of nerve cells. The thickening causes the cells to become misshapen and they fail to function correctly. The symptoms of Alzheimer's disease include memory loss, disorientation and mood changes. Death occurs after several years of decline, and there is no cure. Magnification: x50 at 6x7cm size.