Illustration of tangles of malformed proteins (prions, orange) being produced from brain cells at lower left, and binding to neurons (right) inside the brain. Two different mechanisms are shown: smaller tangles (upper centre) and larger balls of strands (lower centre). Prions cause degenerative brain diseases like Creutzfeldt-Jakob disease (CJD). Some theories also ascribe diseases such as Alzheimer’s to a form of prion disorder.