What type of brain disease is CJD?

Creutzfeldt-Jakob disease, or CJD, is a degenerative brain disorder that presents as rapidly advancing dementia followed by death, according to the National Institute of Neurological Disorders and Stroke, or NINDS. Nine out of 10 of those afflicted with the rare disease die within 12 months from onset.

Symptoms of CJD include impaired judgment, lack of coordination, involuntary movements, depression and blindness, states NINDS. Scientists believe that a type of protein called prion in its infectious form, or a mutation of its genes, may be the cause of CJD. As of 2015, there is no cure, treatment or method of controlling the advance of CJD once it starts.