Brain in Alzheimer's disease. Coloured magnetic resonance imaging (MRI) scan of a sagittal section through the brain of a 72-year-old patient with Alzheimer's disease, focusing on the hippocampus (arrows) in the medial temporal lobe. Alzheimer's is caused by neuron and synapse degeneration and the formation of protein plaques in the brain. This abnormal loss leads to atrophy (wasting) of the affected areas. Symptoms include memory loss, personality changes and confusion. This scan will be used as a reference to track the development of the disease.