Coloured transmission electron micrograph (TEM) of a section through the brain of a patient with Alzheimers disease showing amyloid plaques (pink). 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 Alzheimers disease, which include memory loss, personality changes and confusion. Cellular debris, mainly mitochondria (green), from degenerating neurites can also be seen. The scale bar is equal to one micrometre.