Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Creutzfeldt-Jakob Disease ?
    ### Response:
    Creutzfeldt-Jakob disease (CJD) is a rare, degenerative brain disorder. Symptoms usually start around age 60. Memory problems, behavior changes, vision problems, and poor muscle coordination progress quickly to dementia, coma, and death. Most patients die within a year.
    