Olfactory dysfunction in Guamanian ALS, parkinsonism, and dementia

Objectives: To assess whether olfactory deficits are present in the general Guamanian Chamorro population and to evaluate olfaction in each of the fou r neurodegenerative disease syndromes of Guam: ALS, pure parkinsonism, pure dementia, and the combined parkinsonism-dementia complex (PDC). Background : Olfactory dysfunction was previously reported in patients with PDC of Gua m. Methods: We developed a culturally adjusted olfactory test, battery, der ived from the original University of Pennsylvania Smell Identification Test (UPSIT), and administered this to Chamorro residents with ALS (n = 9), pur e parkinsonism (n = 9), pure dementia (n = 11), PDC (n = 31), and 53 neurol ogically normal Chamorro and 25 North American control subjects. Results: S imilar, marked olfactory dysfunction was found in all four syndromes of Gua manian neurodegenerative disease. This correlated poorly with measures of p arkinsonism and cognition. In the neurologically normal Chamorro control gr oup, six subjects (11%) had very low olfactory scores; these were less than the lowest North American score, raising a question of subclinical neurode generative disease. Conclusions: Marked olfactory deficits are common to al l four Guamanian neurodegenerative syndromes, and suggest the possibility o f similar central neuropathologic substrates. The deficit in the Guamanian ALS group contrasts with idiopathic ALS, in which olfactory function has be en reported to be only slightly compromised.