Odor Identification Deficit as a Predictor of Five-Year Global Cognitive Change: Interactive Effects with Age and ApoE-ε4
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Olfactory impairments are present in common neurodegenerative disorders and predict conversion to dementia in non-demented individuals with cognitive impairment. In cognitively intact elderly, evidence is sparse regarding the role of olfactory deficits in predicting cognitive impairment. The present study investigated predictors of 5-year prospective decline in the Mini-Mental State Examination (MMSE) in a large (n = 501), population-based sample of elderly (65–90 years) individuals. All participants were genotyped for the ApoE gene, assessed for health factors, and were non-demented at the baseline assessment. After partialling out the influences of demographic and health-factors at baseline and dementia at follow-up, poor odor identification ability in combination with older age and the ApoE-ε4 allele predicted larger prospective global cognitive decline. This effect could not be produced by a vocabulary test. In sum, the findings suggest that an olfactory deficit can dissociate between benign and malign global cognitive development in non-demented, very old ε4-carriers, who are at high risk of developing dementia.
KeywordsApoE Odor identification Olfaction Aging Dementia
The Betula Study is funded by the Bank of Sweden Tercentenary Foundation (1988-0082:17), Swedish Council for Planning and Coordination of Research (D1988-0092, D1989-0115, D1990-0074, D1991-0258, D1992-0143, D1997-0756, D1997-1841, D1999-0739, B1999-474), Swedish Council for Research in the Humanities and Social Sciences (F377/1988-2000), the Swedish Council for Social Research (1988-1990: 88-0082, and 311/1991-2000), and the Swedish Research Council (315-2004-6977). The authors acknowledge the contribution to this paper of the VIB—Department of Molecular Genetics at the University of Antwerp, Antwerpen, Belgium, and Rolf Adolfsson at the Department of Psychiatry, Umeå University, to the APOE genotyping of Betula individuals. The authors declare no conflict of interest.
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