In neurodegenerative diseases, clumps of insoluble proteins appear in patients' brains. These aggregates contain proteins that are unique to each disease, such as amyloid beta in Alzheimer's disease, but they are intertwined with small amounts of many other insoluble proteins that are normally present in a soluble form in healthy young individuals. For years, these other proteins were thought to be accidental inclusions in the aggregates, much as a sea turtle might be caught in a net of fish. Now, in a surprising new finding, researchers report that many of the proteins present as minor components of disease aggregates actually clump together as a normal part of aging in healthy individuals.