Olfaction and Aging: A Review of the Current State of Research and Future Directions

Olofsson, Jonas; Ekström, Ingrid; Larsson, Maria; Nordin, Steven

doi:10.1177/20416695211020331

Cited by 35 publications

(24 citation statements)

References 199 publications

(205 reference statements)

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“…Although olfaction shows impairment with normal aging [ 33 ], the magnitude of the impairment in Alzheimer’s patients is profoundly greater than that of typically aging adults. Alzheimer’s patients show significantly greater deficits in odor thresholds, recognition memory, remote odor memory, discrimination, identification, olfactory event-related potentials and functional MRI during olfactory tasks than age matched controls [ 34 , 35 , 36 , 37 , 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease

Wheeler

Murphy

2021

Brain Sciences

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Background: Early biomarkers of prodromal Alzheimer’s disease (AD) are critical both to initiate interventions and to choose participants for clinical trials. Odor threshold, odor identification and odor familiarity are impaired in AD. Methods: We investigated the relative abilities of standard screening (MMSE) and olfactory measures to predict transitions from cognitively normal (CN) to mild cognitive impairment (MCI), from CN to AD, and MCI to AD. The archival sample of 497, from the UCSD ADRC, included participants who were CN, MCI, AD and converters to MCI or AD. Apoe ε4 status, a genetic risk factor, was available for 256 participants, 132 were ε4 carriers. A receiver operating characteristic curve (ROC) curve plots the trade-off between sensitivity and specificity. Area under the ROC curve (AUC) was used to determine diagnostic accuracy. Results: Different measures were better predictors at specific stages of disease risk; e.g., odor familiarity, odor identification and the combination showed higher predictive value for converting from MCI to AD in ε4 carriers than the MMSE. Combining odor familiarity and odor identification produced an AUC of 1.0 in ε4 carriers, MMSE alone was 0.58. Conclusions: Olfactory biomarkers show real promise as non-invasive indicators of prodromal AD. The results support the value of combining olfactory measures in assessment of risk for conversion to MCI and to AD.

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Section: Introductionmentioning

confidence: 99%

Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease

Wheeler

Murphy

2021

Brain Sciences

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“…Although longitudinal studies on predictors of olfactory decline are sparse, similar small effect sizes have been observed regarding olfactory loss (Ekström et al 2020;Schubert et al 2015). Previous research suggests that olfactory decline in the adult population is mainly driven by either aging or neurodegenerative processes (as reviewed in Olofsson et al 2021). Apart from these two major factors, interindividual characteristics related to demographics, lifestyle, health, and genetic factors likely play a role.…”

Section: Discussionmentioning

confidence: 78%

“…2015 ). Previous research suggests that olfactory decline in the adult population is mainly driven by either aging or neurodegenerative processes (as reviewed in Olofsson et al. 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Environmental Air Pollution and Olfactory Decline in Aging

Ekström

Rizzuto

Grande

et al. 2022

Environ Health Perspect

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Background: Olfactory impairment is increasingly common with older age, which may be in part explained by cumulative effects of exposure to inhaled toxins. However, population-based studies investigating the relationship between air pollution and olfactory ability are scarce. Objectives: We aimed to investigate associations between exposure to common air pollutants and longitudinal change in odor identification. Methods: Our study of 2,468 participants ( ; 61.1% female), of which 1,774 participants ( ; 61.9% female) had at least two olfactory assessments over 12 y of follow-up from the Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), Stockholm, Sweden. Participants were free from cognitive impairment and neurodegenerative disease at baseline. Odor identification ability was assessed with Sniffin’ Sticks. Change in olfactory performance was estimated with linear mixed models. Exposure to two major airborne pollutants [particulate matter with aerodynamic diameter ( ) and nitrogen oxides ( )] for the 5 y preceding baseline was assessed using spatiotemporal dispersion models for outdoor levels at residential addresses. Results: Participants showed significant decline in odor identification ability for each year in the study { [95% confidence interval (CI): , ; ]}. After adjustment for all covariates, residents of third [ (95% CI: , ; )] and fourth [ (95% CI: , ; )] exposure quartiles of had faster rates of olfactory decline than residents from the first quartile. Similar results were observed for the third [ (95% CI: , ; )] and fourth [ (95% CI: , ; ) quartiles of ]. Discussion: Our results suggest an association between air pollution exposure and subsequent olfactory decline. We speculate that cumulative effects of airborne pollutants on the olfactory system may be one underlying cause of olfactory impairment in aging. https://doi.org/10.1289/EHP9563

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“…Possibly less well known is the apparent negative impact of age on perceptual judgments involving other modalities. In brief, an increase in chronological age has been found to negatively impact olfactory perception (e.g., Doty et al, 2011 ; Zhang and Wang, 2017 ; Olofsson et al, 2021 ), haptic perception (e.g., Thompson et al, 1965 ; Kleinman and Brodzinsky, 1978 ; Norman et al, 2016 ), and gustatory perception (e.g., Kaneda et al, 2000 ; Murphy et al, 2002 ; Fukunaga et al, 2005 ).…”

Section: Introductionmentioning

confidence: 99%

Age and Auditory Spatial Perception in Humans: Review of Behavioral Findings and Suggestions for Future Research

Russell

2022

Front. Psychol.

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It has been well documented, and fairly well known, that concomitant with an increase in chronological age is a corresponding increase in sensory impairment. As most people realize, our hearing suffers as we get older; hence, the increased need for hearing aids. The first portion of the present paper is how the change in age apparently affects auditory judgments of sound source position. A summary of the literature evaluating the changes in the perception of sound source location and the perception of sound source motion as a function of chronological age is presented. The review is limited to empirical studies with behavioral findings involving humans. It is the view of the author that we have an immensely limited understanding of how chronological age affects perception of space when based on sound. In the latter part of the paper, discussion is given to how auditory spatial perception is traditionally conducted in the laboratory. Theoretically, beneficial reasons exist for conducting research in the manner it has been. Nonetheless, from an ecological perspective, the vast majority of previous research can be considered unnatural and greatly lacking in ecological validity. Suggestions for an alternative and more ecologically valid approach to the investigation of auditory spatial perception are proposed. It is believed an ecological approach to auditory spatial perception will enhance our understanding of the extent to which individuals perceive sound source location and how those perceptual judgments change with an increase in chronological age.

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Olfaction and Aging: A Review of the Current State of Research and Future Directions

Cited by 35 publications

References 199 publications

Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease

Olfactory Measures as Predictors of Conversion to Mild Cognitive Impairment and Alzheimer’s Disease

Environmental Air Pollution and Olfactory Decline in Aging

Age and Auditory Spatial Perception in Humans: Review of Behavioral Findings and Suggestions for Future Research

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