Distinguishing Alzheimer's disease and dementia with Lewy bodies using cognitive and olfactory measures

Given poor sensitivity of the diagnostic criteria in identifying dementia with Lewy bodies (DLB), the use of cognitive and olfactory measures to distinguish Alzheimer's disease (AD) from DLB was assessed.

Twenty-six patients with DLB and 60 patients with AD were administered several cognitive measures and the Brief Smell Identification Task (BSIT).

Patients with DLB performed significantly worse on the BSIT and visuoconstruction tasks than patients with AD, but significantly better on delayed recall of a word list. Sensitivity and specificity of these measures in identifying DLB are presented for each of these tasks alone and in combination. The best balance of sensitivity and specificity was found with a combination of the Hopkins Verbal Learning Test and BSIT (81% sensitivity, 90% specificity).

These data have practical implications by providing cut scores than can be used to emphasize either specificity or sensitivity in identifying patients with DLB.