Olfactory Dysfunction in Alzheimer's Disease

Recent evidence suggesting involvement of the central olfactory system in Alzheimer's disease (AD) was assessed by contrasting olfactory and visual discrimination in 15 probable AD subjects and 6 healthy aged controls. Control subjects performed better than AD subjects on both tasks. Mild AD subjects performed better than moderate AD subjects on visual discrimination, although the two groups did not differ on olfactory discrimination. Positron emission tomographic (PET) studies with (F-18)2-fluoro-2-deoxy-D-glucose performed on 11 of the AD subjects showed no relation between olfactory performance and cerebral metabolic asymmetries, but relations to visual discrimination were found.