Coexistence of Creutzfeldt-Jakob disease and Alzheimer's disease in the same patient.

We report the case of a 73-year-old patient in whom a diagnosis of Creutzfeldt-Jakob disease, suggested by the clinical course, was verified by the neuropathologic finding of widespread spongiform change and astrogliosis, the presence of proteinase-resistant protein in brain extracts, and the experimental transmission of spongiform encephalopathy to primates inoculated with brain tissue. However, neuropathologic examination also revealed a profusion of senile and neuritic plaques and neurofibrillary tangles that reacted with antibody to the amyloid beta-protein characteristic of Alzheimer's disease, but not with antibody to the scrapie amyloid protein characteristic of Creutzfeldt-Jakob disease.