Clinically Unsuspected Prion Disease Among Patients With Dementia Diagnoses in an Alzheimer's Disease Database

Brain tissue analysis is necessary to confirm prion diseases. Clinically unsuspected cases may be identified through neuropathologic testing.

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.

Of 6000 eligible patients in the NACC database, 7 (0.12%) were clinically unsuspected but autopsy-confirmed prion disease cases.

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.