Severity of cognitive impairment and the clinical diagnosis of AD with Lewy bodies

Objective: 1) To examine the clinical differences between AD and AD with Le wy bodies (AD+LB); and 2) to determine the accuracy of Consensus guidelines for the clinical diagnosis of dementia with Lewy bodies (DLB) at different levels of dementia severity. Methods: The authors examined the clinical ch aracteristics of 185 patients with pathologically diagnosed AD alone and 60 with ADS LB. The relationship between clinical symptoms and AD+LB was dete rmined by multivariate analyses, controlled by age, duration of symptoms, p resence of cerebrovascular disease, and dementia severity. Results: Mild de mentia syndrome: No specific clinical symptom was associated with the prese nce of AD+LB. The sensitivity of the diagnosis of DLB was 62% and specifici ty was 54%. Moderate dementia syndrome: Extrapyramidal signs (EPS), especia lly cogwheel rigidity, and major depression were associated with AD+LB. The sensitivity for DLB was 82% and specificity was 31%. Severe dementia syndr ome: Cogwheel rigidity and diurnal hypersomnia were associated with AD+LB. The sensitivity for DLB was 93% and specificity was 16%. Conclusions: The p resence of EPS is not useful in differentiating AD+LB from AD in patients w ith mild dementia. However, as the disease progressed, they emerge as defin ing features, especially cogwheel rigidity. The accuracy of AD+LB diagnosis varies according the severity of the dementia syndrome. The low sensitivit y and specificity in AD+LB patients with mild dementia suggest that in earl y stages AD+LB patients do not present the clinical characteristics of DLB. By contrast, the high sensitivity and low specificity for the diagnosis of DLB in moderate/severe dementia stages suggests that; AD patients can also have characteristic symptoms of DLB. These results indicate that; the ante mortem diagnosis of AD +LB is difficult in all dementia stages, and better clinical and biologic differentiations of these entities are needed.