Researchers have found new evidence that confirms the significance of a protein that neuroscientists call tau to the development of Alzheimer's disease. While earlier studies have focused on tau's aggregation into twisted structures known as "neurofibrillary tangles," the new work emphasizes intermediary steps between single protein units and the much larger tangles – small assemblages of two, three, four or more proteins, which the investigators believe are the most toxic entities in Alzheimer's.