Olfactory identification testing as a predictor of the development of Alzheimer's dementia: A systematic review

Sun, Gordon H.; Raji, Cyrus A.; MacEachern, Mark; Burke, James F.

doi:10.1002/lary.23365

Cited by 78 publications

(76 citation statements)

References 67 publications

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“…36,37 A 2012 systematic review identified 2 prospective, longitudinal studies that examined the utility of odor identification testing as a predictor of the development of AD, defined more rigorously with clinical criteria. 3,38,39 A recent analysis added substantively to this area, showing that baseline odor identification deficits were predictive of cognitive decline and transition to AD dementia in a large multiethnic population-based cohort of patients without dementia. 2 Our study, when continued longitudinally, offers the opportunity to test this hypothesis at an even earlier stage, with participants who do not have memory concerns or cognitive deficits.…”

Section: Resultsmentioning

confidence: 99%

Odor identification and Alzheimer disease biomarkers in clinically normal elderly

et al. 2015

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Objectives: Our objective was to investigate cross-sectional associations between odor identification ability and imaging biomarkers of neurodegeneration and amyloid deposition in clinically normal (CN) elderly individuals, specifically testing the hypothesis that there may be an interaction between amyloid deposition and neurodegeneration in predicting odor identification dysfunction.Methods: Data were collected on 215 CN participants from the Harvard Aging Brain Study. Measurements included the 40-item University of Pennsylvania Smell Identification Test and neuropsychological testing, hippocampal volume (HV) and entorhinal cortex (EC) thickness from MRI, and amyloid burden using Pittsburgh compound B (PiB) PET. A linear regression model with backward elimination (p , 0.05 retention) evaluated the cross-sectional association between the University of Pennsylvania Smell Identification Test and amyloid burden, HV, and EC thickness, assessing for effect modification by PiB status. Covariates included age, sex, premorbid intelligence, APOE e4 carrier status, and Boston Naming Test.Results: In unadjusted univariate analyses, worse olfaction was associated with decreased HV

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Section: Resultsmentioning

confidence: 99%

Odor identification and Alzheimer disease biomarkers in clinically normal elderly

et al. 2015

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“…These elements are also found throughout the olfactory nervous system in AD patients, justifying the early association between AD and olfactory loss [44]. Although some authors have found that even the OE in AD patients contains pathologically phosphorylated tau filaments [51], other authors have not been able to confirm this finding [52].…”

Section: Introductionmentioning

confidence: 95%

“…AD is a widespread disease and the most common cause of dementia among the elderly with an annual incidence of 1 % in persons aged 60-70 years and 6-8 % in those aged 85 years or more [44]. By age 65, the incidence of AD seems to double every 5 years.…”

Section: Introductionmentioning

confidence: 99%

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Olfaction deterioration in cognitive disorders in the elderly

et al. 2015

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Alzheimer's and Parkinson's diseases are both neurodegenerative disorders typically found in the elderly. As both diseases are characterized by the early presence of dysosmia, simple validated smell tests could very well help clinicians in the early diagnosis of these neuropathological conditions. Elderly patients complaining of smell loss and found to be dysosmic, by means of validated olfactory tests, should be neurologically evaluated as early as possible to detect slight motor abnormalities in an at-risk population.

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“…Olfactory testing can, at least at the group level, reliably differentiate individuals with AD from normal controls [6,7]; olfaction declines during the evolution of AD [8]; and in longitudinal studies olfactory testing contributes to the prediction of who will later develop MCI or clinical AD [9-11, 12•, 13]. In 34 individuals cognitively intact prior to death, the extent of AD pathology at autopsy in central olfactory structures correlated significantly with the results on the Brief Smell Identification Test, a simple test of olfaction, suggesting that olfactory testing might help detect preclinical disease [14].…”

Section: Introductionmentioning

confidence: 99%

The Role of Olfactory Challenge Tests in Incipient Dementia and Clinical Trial Design

Schofield

Finnie

Yong

2014

Curr Neurol Neurosci Rep

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The brain changes associated with Alzheimer's disease (AD) develop slowly over many years before the onset of dementia. Biomarkers for AD that allow its detection during this clinically silent phase will be hugely important when disease-modifying treatments that halt or slow its progression become available. Early detection, leading to early treatment, may in some cases avert dementia. Biomarkers aid our understanding of the presymptomatic stages of the disease and enable the identification of individuals with early disease who, by participating in clinical trials of investigational treatments with disease-modifying potential, contribute unique and vital information necessary to evaluate novel therapies. Most currently available AD biomarkers are expensive and not widely available and there are major efforts underway to find cheaper, simpler options. The olfactory system is affected by AD and the results from simple and inexpensive tests of the sense of smell, especially when paired with other information, can help identify individuals early in the disease. We review recent literature relevant to the use of simple olfactory tests, including some novel approaches, as aids to the early detection of AD. We consider their possible role in the design and conduct of clinical trials and suggest how in the future, when more effective treatments become available, they might be integrated into screening programs for early AD detection.

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Olfactory identification testing as a predictor of the development of Alzheimer's dementia: A systematic review

Abstract: 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.

Cited by 78 publications

References 67 publications

Odor identification and Alzheimer disease biomarkers in clinically normal elderly

Odor identification and Alzheimer disease biomarkers in clinically normal elderly

Olfaction deterioration in cognitive disorders in the elderly

The Role of Olfactory Challenge Tests in Incipient Dementia and Clinical Trial Design

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