Clinically Unsuspected Prion Disease among Patients with Dementia Diagnoses in an Alzheimer's Disease Database

Abstract

Background: Brain tissue analysis is necessary to confirm prion diseases. Clinically unsuspected cases may be identified through neuropathologic testing. Methods: National Alzheimer's Coordinating Center (NACC) Minimum and Neuropathologic Data Set for 1984 to 2005 were reviewed. Eligible patients had dementia, underwent autopsy, had available neuropathologic data, belonged to a currently funded Alzheimer's Disease Center (ADC), and were coded as having an Alzheimer's disease clinical diagnosis or a nonprion disease etiology. For the eligible patients with neuropathology indicating prion disease, further clinical information, collected from the reporting ADC, determined whether prion disease was considered before autopsy. Results: Of 6000 eligible patients in the NACC database, 7 (0.12%) were clinically unsuspected but autopsy-confirmed prion disease cases. Conclusion: The proportion of patients with dementia with clinically unrecognized but autopsy-confirmed prion disease was small. Besides confirming clinically suspected cases, neuropathology is useful to identify unsuspected clinically atypical cases of prion disease.