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Olfactory identification testing as a predictor of the development of Alzheimer's dementia: A systematic review
Author(s) -
Sun Gordon H.,
Raji Cyrus A.,
MacEachern Mark P.,
Burke James F.
Publication year - 2012
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1002/lary.23365
Subject(s) - hyposmia , psycinfo , dementia , meta analysis , medicine , systematic review , olfaction , neurocognitive , prospective cohort study , cohort study , medline , cohort , psychology , cognition , psychiatry , disease , neuroscience , covid-19 , political science , infectious disease (medical specialty) , law
Abstract Objectives/Hypothesis: To evaluate the utility of olfactory identification tests as prognostic instruments for Alzheimer's dementia (AD). Study Design: Systematic review. Methods: In accordance with PRISMA guidelines, PubMed and Ovid MEDLINE, EMBASE, ISI Web of Science, PsycINFO, the Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials were searched to determine the quality and quantity of longitudinal and cross‐sectional research on this topic. Results: Two prospective longitudinal cohort studies and 30 cross‐sectional studies met inclusion criteria. The prospective longitudinal studies evaluated subjects with or without mild cognitive impairment (MCI) while also using olfactory identification testing as part of a neurocognitive evaluation. The first study reported an increased risk of later onset of AD in subjects with baseline hyposmia, whereas the second study suggested a possible relationship between decreased olfaction in participants with MCI and conversion to AD but was inconclusive due to low follow‐up rates. Wide variability in the type of olfactory identification test used and the reporting of results precluded meta‐analysis. The cross‐sectional studies demonstrated a positive association between poorer performance on olfactory identification testing and AD. Conclusions: Although there is evidence suggesting an association between decreased olfaction and AD, rigorously designed longitudinal cohort studies are necessary to clarify the value of olfactory identification testing in predicting the onset of AD.