| 1. |
- Cedres, Nira, et al.
(författare)
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Subjective Impairments in Olfaction and Cognition Predict Dissociated Behavioral Outcomes
- 2022
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Ingår i: The journals of gerontology. Series B, Psychological sciences and social sciences. - : Oxford University Press (OUP). - 1079-5014 .- 1758-5368. ; 78:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Self-rated subjective cognitive decline (SCD) and subjective olfactory impairment (SOI) are associated with objective cognitive decline and dementia. However, their relationship and co-occurrence is unknown. We aimed to (a) describe the occurrence of SOI, SCD and their overlap in the general population; (b) compare SOI and SCD in terms of longitudinal associations with corresponding objective olfactory and cognitive measures; and (c) describe how SOI and SCD may lead to distinct sensory and cognitive outcomes.Methods: Cognitively unimpaired individuals from the third wave of the Swedish population-based Betula study (n = 784, aged 35–90 years; 51% females) were split into self-rated SOI, SCD, overlapping SCD + SOI, and controls. Between-subject and within-subject repeated-measures MANCOVA were used to compare the groups regarding odor identification, cognition, age, sex, and education. Spearman correlation was used to assess the different patterns of association between olfaction and cognition across groups.Results: SOI was present in 21.1%, whereas SCD was present in 9.9% of participants. According to a chi-square analysis, the SCD + SOI overlap (2.7%) is on a level that could be expected if the phenomena were independent. Odor identification in SOI showed decline at the 10-year follow-up (n = 284) and was positively associated with cognition. The SOI and SCD groups showed distinct cognitive-olfactory profiles at follow-up.Conclusions: SOI occur independently of SCD in the population, and these risk factors are associated with different cognitive and olfactory outcomes. The biological causes underlying SOI and SCD, as well as the risk for future cognitive impairment, need further investigation.
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| 2. |
- Dong, Yi, et al.
(författare)
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Dementia screening in rural-dwelling Chinese older adults : The utility of a smell test and the self-rated AD8
- 2022
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 70:4, s. 1106-1116
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Tidskriftsartikel (refereegranskat)abstract
- Background: Olfactory impairment is associated with dementia in clinical settings. We examined the relationship of olfactory identification function with all-cause dementia, Alzheimer's disease (AD), and vascular dementia (VaD) and assessed the discriminative ability of the Sniffin' Sticks Identification Test (SSIT), the self-rated Ascertain Dementia 8-item Questionnaire (AD8), and their combination for dementia detection among rural-dwelling older adults in China.Methods: This population-based cross-sectional study included 4481 participants (age ≥ 65 years; 56.8% women; 38.1% illiteracy) living in rural communities. The 16-item SSIT was performed to assess olfactory identification function. The self-rated AD8 was administered to participants for cognitive status. We diagnosed dementia, AD, and VaD following the international criteria. Data were analyzed with logistic regression models and receiver operating characteristic curve.Results: Of the 4481 participants, dementia was diagnosed in 139 persons (3.1%), including 92 with AD and 42 with VaD. The SSIT score (range, 0–16) was associated with multiadjusted odds ratios of 0.83 (95% CI: 0.79–0.88) for dementia, 0.84 (0.79–0.90) for AD, and 0.79 (0.71–0.87) for VaD. The area under the curve for the discrimination between participants with and without dementia was 0.73 (95% CI: 0.69–0.77) for SSIT score ≤ 8 alone, 0.86 (0.82–0.89) for self-rated AD8 score ≥ 3 alone, and 0.89 (0.86–0.92) for their combination using a logistic model.Conclusions: Olfactory impairment is a clinical marker for all-cause dementia, AD, and VaD. The smell identification test, in combination with the brief self-rated cognitive screening tool, is accurate for screening dementia among rural-dwelling Chinese older adults with no or limited education.
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| 3. |
- Ekström, Ingrid, 1988-, et al.
(författare)
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Environmental Air Pollution and Olfactory Decline in Aging
- 2022
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Ingår i: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 130:2
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Tidskriftsartikel (refereegranskat)abstract
- 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 (mean age = 72.3 y; 61.1% female), of which 1,774 participants (mean age = 70.5 y; 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 <= 2.5 mu m (PM2.5) and nitrogen oxides (NOx)] 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 {f3 = - 0.20 [95% confidence interval (CI): -0.22, 0.18; p < 0.001]}. After adjustment for all covariates, residents of third [f3= - 0.09 (95% CI: -0.14, -0.04; p < 0.001)] and fourth [f3 = - 0.07 (95% CI: -0.12, -0.02; p = 0.005)] exposure quartiles of PM2.5 had faster rates of olfactory decline than residents from the first quartile. Similar results were observed for the third [f3= - 0.05 (95% CI: -0.10, -0.01; p = 0.029)] and fourth [f3= - 0.07 (95% CI: -0.11, -0.02; p = 0.006) quartiles of NOx].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.
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| 4. |
- Ekström, Ingrid, 1988-
(författare)
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Human olfaction : Associations with longitudinal assessment of episodic memory, dementia, and mortality risk
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A declining sense of smell is a common feature in older age. Above and beyond diminished smelling capacity due to normal processes of human aging, impairments in olfactory function have also been linked to numerous ill-health related outcomes, such as cognitive dysfunctions, dementia pathology and even an increased risk of death. Based on population-based data from the Swedish Betula Prospective Cohort Study, the aim of this thesis was to further our understanding regarding the role of olfaction in long-term memory decline, dementia, and mortality. Furthermore, this thesis investigated the predictive utility of self-reported olfactory dysfunction for assessing the risk of conversion to later dementia and to mortality, as well as the predictive utility of long-term subjective olfactory decline for an actual long-term decline in odor function. Study I explored associations of olfactory deficits with memory decline and found that impairments in an odor identification test were related to an ongoing and long-term decline in episodic memory only in carriers of the e4 allele of the Apolipoprotein E, a genetic risk factor for Alzheimer’s disease. Study II investigated the predictive utility of olfactory ability for conversion to common forms of dementia in participants with intact baseline cognition during a follow-up time-span of 10 years. The results showed that lower odor identification scores, as well as subjectively assessed odor impairment, were associated with an increased risk for dementia conversion, and that the effects of objective and subjective odor function were cumulative. Study III investigated whether olfactory ability could predict mortality and showed that lower odor identification scores, as well as subjective odor impairments, were associated with an elevated risk of death within a follow-up time-span of approximately 10 years. Crucially, this effect could not be explained by dementia conversion prior to death. Study IV showed that a subjectively assessed long-term and ongoing olfactory decline was predictive of an objectively assessed long-term and ongoing decline in odor function. Subjective olfactory impairments might thus be indicative of an actual olfactory decline in older adults. Overall, the findings of this thesis indicate that sense of smell is closely related to processes of memory decline and dementia as well as mortality in older adults. Furthermore, the results of these investigations shed a new light on the role of subjectively experienced olfactory decline, which might reflect an actual intra-individual change in olfactory ability in older adults.
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| 5. |
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| 6. |
- Ekström, Ingrid, 1988-, et al.
(författare)
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Subjective Olfactory Loss in Older Adults Concurs with Long-Term Odor Identification Decline
- 2019
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Ingår i: Chemical Senses. - Oxford : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 44:2, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- Olfactory impairments may provide early indications of future health outcomes in older adults. Thus, an important question concerns whether these impairments can be self-assessed. Previous findings of cross-sectional studies indicate low correlations between self-reported olfactory function and objective olfactory performance. On the other hand, subjective olfactory impairments predict future dementia and mortality in longitudinal settings. No previous study has assessed the relationship between subjectively and objectively measured decline in olfaction over time. Based on data for 903 older adults derived from the Betula Study, a Swedish population-based prospective study, we tested whether rate-of-change in odor identification could be predicted from subjective olfactory decline over a time span of 10 years during which subjective and objective odor functions were assessed on 2 or 3 test occasions. Indeed, we found that participants who experienced subjective olfactory decline over the study period also had significantly steeper rates of decline in odor identification, even after adjusting for demographic, cognitive, and genetic factors that previously have been associated with performance in odor identification. This association was, however, not present in a subsample with baseline cognitive impairment. We interpret these results as evidence that when asked about whether they have an olfactory impairment or not, older persons are assessing intraindividual olfactory changes, rather than interindividual differences. Our results indicate that subjective olfactory loss reflects objective olfactory decline in cognitively intact older adults. This association might be harnessed to predict health outcomes and highlights the need to develop effective olfactory self-assessments.
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| 7. |
- Hörberg, Thomas, et al.
(författare)
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Incongruent odors suppress perceptual categorization of visual objects : Behavioral and ERP evidence
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Visual stimuli often dominate non-visual stimuli during multisensory perception, and evidence suggests higher cognitive processes prioritize visual over non-visual stimuli during divided attention. Visual stimuli may therefore have privileged access to higher mental processing resources, relative to other senses, and should be disproportionally distracting when processing incongruent cross-sensory stimuli. We tested this assumption by comparing visual processing with olfaction, a “primitive” sensory channel that detects potentially hazardous chemicals by alerting attention. Behavioral and event-related brain potentials (ERPs) were assessed in a bimodal object categorization task with congruent or incongruent odor-picture pairings and a delayed auditory response target. For congruent pairings, accuracy was higher for visual compared to olfactory decisions. However, for incongruent pairings, reaction times (RTs) were faster for olfactory decisions, suggesting incongruent odors interfered more with visual decisions, thereby showing an “olfactory dominance effect”. Categorization of incongruent pairings engendered a late “slow wave” ERP effect. Importantly, this effect had a later amplitude peak and longer latency during visual decisions, likely reflecting additional categorization effort for visual stimuli. In sum, contrary to what might be inferred from theories of ”visual dominance”, incongruent odors may in fact uniquely attract mental processing resources during perceptual incongruence.
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| 8. |
- Hörberg, Thomas, 1979-, et al.
(författare)
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Olfactory Influences on Visual Categorization : Behavioral and ERP Evidence
- 2020
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Ingår i: Cerebral Cortex. - : Oxford University Press (OUP). - 1047-3211 .- 1460-2199. ; 30:7, s. 4220-4237
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Tidskriftsartikel (refereegranskat)abstract
- Visual stimuli often dominate nonvisual stimuli during multisensory perception. Evidence suggests higher cognitive processes prioritize visual over nonvisual stimuli during divided attention. Visual stimuli should thus be disproportionally distracting when processing incongruent cross-sensory stimulus pairs. We tested this assumption by comparing visual processing with olfaction, a “primitive” sensory channel that detects potentially hazardous chemicals by alerting attention. Behavioral and event-related brain potentials (ERPs) were assessed in a bimodal object categorization task with congruent or incongruent odor–picture pairings and a delayed auditory target that indicated whether olfactory or visual cues should be categorized. For congruent pairings, accuracy was higher for visual compared to olfactory decisions. However, for incongruent pairings, reaction times (RTs) were faster for olfactory decisions. Behavioral results suggested that incongruent odors interfered more with visual decisions, thereby providing evidence for an “olfactory dominance” effect. Categorization of incongruent pairings engendered a late “slow wave” ERP effect. Importantly, this effect had a later amplitude peak and longer latency during visual decisions, likely reflecting additional categorization effort for visual stimuli in the presence of incongruent odors. In sum, contrary to what might be inferred from theories of “visual dominance,” incongruent odors may in fact uniquely attract mental processing resources during perceptual incongruence.
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| 9. |
- Laukka, Erika J., et al.
(författare)
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Markers of olfactory dysfunction and progression to dementia : A 12-year population-based study
- 2023
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Ingår i: Alzheimer's & Dementia. - : John Wiley & Sons. - 1552-5260 .- 1552-5279. ; 19:7, s. 3019-3027
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: We evaluated markers of olfactory dysfunction (OD) for estimating hazard of dementia in older adults.Methods: Mild (hyposmia) and severe (anosmia) OD was classified in a population-based study of dementia-free persons (SNAC-K; n = 2473; mean age = 70 years) using the Sniffin sticks odor identification task. Combined variables were created for objective and subjective OD and for OD and APOE status. Hazard of dementia across 12 years was estimated with Cox regression.Results: OD was associated with increased hazard of dementia (2.01; 95% confidence interval [CI] 1.60-2.52), with the strongest association for anosmia (2.92; 95% CI 2.14-3.98). Results remained consistent after adjusting for potential confounders and across age and sex subgroups. APOE ε4 carriers with anosmia had the highest hazard of dementia (ε4: 6.95; 95% CI 4.16-11.62; ε4/ε4: 19.84; 95% CI 6.17-63.78).Discussion: OD is associated with increased risk of dementia, especially severe impairment in combination with genetic risk of Alzheimer's disease.
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| 10. |
- Olofsson, Jonas K., et al.
(författare)
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Incongruent odors suppress perceptual categorization of visual objects
- 2019
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Konferensbidrag (refereegranskat)abstract
- During multisensory experiences, visual stimuli typically suppress non-visual stimuli. Such ”visual dominance” effects might stem from inhibition across sensory systems. Does visual dominance generalize to odor-visual pairings? We developed a categorization task (fruits vs flowers) with congruent and incongruent odor-picture pairings and a delayed auditory response target that informed about categorization modality (olfactory vs visual). We investigated behavioral and cortical (ERP) responses. For congruent pairings, we found better accuracy for visual decisions. However, for incongruent pairings, we insteadobserved faster RTs for olfactory decisions. Incongruent olfactory stimuli thus interfere more with visualdecisions than vice versa. Our ERP results from auditory targets on incongruent trials gave supporting evidence of olfactory suppression over visual perception; higher P300 amplitudes were more strongly correlated with faster RTs during visual categorization. A late “slow wave” ERP effect had later onset andlonger latency during visual vs olfactory decisions. This indicates that in order to rapidly and successfully categorize visual stimuli (and ignore incongruent odors), participants need to allocate additional attentional and working memory resources. In sum, both behavioral and ERP effects suggest a higher level of interference from incongruent olfactory, compared to visual, input. These findings suggest that asymmetric inhibition across sensory systems is a fruitful way of studying sensory dominance, and that olfactory stimuli can dominate visual stimuli, refuting the general notion of ”visual dominance”.
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