Olfactory deficits in Alzheimer's disease.

Altered olfactory function may be important clinically and theoretically in Alzheimer's disease (AD). Initial evidence of poor olfactory recognition performance in AD was followed by other reports of hyposmia in this disorder. Although two of these studies have found significantly better performance in other demented groups, the utility of olfactory testing in the differential diagnostic workup of dementia may have limitations. Neuroanatomical and neurochemical studies relevant to AD and olfaction are reviewed. Finally, the effects of aging on olfactory performance is discussed. It is concluded that these effects cannot be adequately assessed without rigorous control for cognitive status in sampled cohorts.