Successful, rational, prevention strategies ultimately come from better understanding of the causes and mechanisms of disease. By definition, SUDEP is unexplained: we do not know why it happens, which currently makes prevention very difficult. SUDEP occurs when the brain is affected by epilepsy, and it may relate to individual seizures. We possess a unique archive of brain tissue from people who died of SUDEP and others who did not. We plan to examine and compare these brains in detail, and determine whether there are differences that can give us clues to the cause of SUDEP.