Cerebral amyloid angiopathy (CAA) is a group of diseases in which protein deposits in blood vessels of the brain can allow blood to leak out and cause hemorrhagic (bleeding) strokes. At the molecular level, it is also closely related to Alzheimer's disease (AD) through the protein amyloid beta-peptide. Amyloid deposits are also involved in a number of other neurodegenerative diseases, including Parkinson’s disease, Creutzfeldt-Jacob’s and Huntington´s diseases.