CLINICOPATHOLOGICAL STUDY OF PROBABLE ALZHEIMER-DISEASE - ASSESSMENT OF CRITERIA FOR EXCLUDING CEREBROVASCULAR-DISEASE

The National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer Disease and Related Disorders Association criteria f or probable Alzheimer disease (AD) require exclusion of non-AD dementi a-producing conditions but do not specify how the non-AD conditions ar e to be identified. We addressed this issue for the case of cerebrovas cular disease (CVD) by defining exclusion rules based on commonly desc ribed clinical features: (a) history of strokelike episodes; (b) histo ry of stepwise cognitive decline; (c) focal deficits on neurological e xamination; and (d) evidence of significant CVD on neuroimaging. We ap plied these rules retrospectively to clinical records for 92 cognitive ly impaired patients who otherwise met criteria for probable AD and wh ose brains were subsequently available for postmortem examination. We used Fisher's exact rest to assess the effectiveness of the exclusion rules in predicting the presence of CVD on autopsy. Prediction was bet ter than chance when all four clinical features were used together (p = 0.0008) and when the stepwise decline or neuroimaging criteria were used alone (p = 0.03 and p = 0.05, respectively). Overall, the CVD exc lusion rules were deficient because of low accuracy (50.0%) and low se nsitivity (52.6%). These results support provisional use of the CVD cr iteria chosen for this study but suggest that modifications are needed for acceptable diagnostic accuracy and sensitivity to be achieved.