Professor Donna Wilcock describes amyloid plaques as clumps of protein in the brain that are one of the three hallmarks of Alzheimer's disease.
Amyloid plaques are, I would say, clumps of protein that are in the brain in the extracellular space, meaning that they are outside of any cells. They are just situated between neurons within the brain, and these are composed of multiple amyloid beta peptides. So, the a-beta peptide is a very short, 40 or 42 amino acid long protein. When you get multiple amyloid beta peptides coming together, they form an insoluble piece of protein called an amyloid plaque. So this is one of the three pathological markers that we know cause Alzheimer’s disease.