Transmission electron micrograph (TEM) showing an amyloid plaque (one at lower centre left) in a brain with Alzheimer's disease. Amyloid plaques are insoluble aggregates of beta-amyloid protein. They are thought to cause cell death and disrupt cell function, leading to the symptoms of Alzheimer's disease, which include memory loss, personality changes and confusion. Magnification: x3,800 when printed at 10 centimetres wide.