Odor identificatiOn and cognitive abilities in alzheimer's disease

Abstract

Research results indicate systemic odor identification deficits in patients with Alzheimer's disease (AD). The aims of this study were: 1) to compare the ability to identify different odors and to compare cognitive status among patients with AD, patients with vascular dementia (VaD) and a comparison group of elderly persons; 2) to test the effciency of olfactory and neuropsychological measures to classify patients and 3) to relate the odor identification ability with cognitive functioning for each group, respectively. The participants were 15 patients with AD, 11 patients with VaD and 30 non-demented elderly persons, age range 58 to 90. To assess olfactory function, we used the Scandinavian Odor-Identification Test. To assess cognitive functions, we used the Dementia Rating Scale-2, the Clock Drawing Test, the Boston Naming Test and the Category Fluency Test. The ANOVA showed that patients with AD correctly identifed significantly fewer odors presented to them compared to patients with VaD and control group. Patients with AD achieved significantly lower scores on all neuropsychological measures compared to the control group and differ in the DRS-2 total score, initiation/perseveration, constructive and naming abilities comparing to patients with VaD. Discriminant analysis showed that category fluency and olfactory identification were the best predictors of AD. Significant correlations were found between the olfactory and initiation/perseveration, memory and animal naming abilities for patients with AD. Differences among patients with AD, VaD and elderly persons exist in their abilities to identify odors. The findings suggest that olfactory functional testing in combination with memory testing are important. © Versita Sp. z o.o.