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Olfactory Impairment and Subjective Olfactory Complaints Independently Predict Conversion to Dementia: A Longitudinal, Population-Based Study
Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
Stockholm University, Faculty of Social Sciences, Department of Psychology, Perception and psychophysics.
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2014 (English)In: Journal of the International Neuropsychological Society, ISSN 1355-6177, E-ISSN 1469-7661, Vol. 20, no 2, p. 209-217Article in journal (Refereed) Published
Abstract [en]

We examined whether conversion to dementia can be predicted by self-reported olfactory impairment and/or by an inability to identify odors. Common forms of dementia involve an impaired sense of smell, and poor olfactory performance predicts cognitive decline among the elderly. We followed a sample of 1529 participants, who were within a normal range of overall cognitive function at baseline, over a 10-year period during which 159 were classified as having a dementia disorder. Dementia conversion was predicted from demographic variables, Mini-Mental State Examination score, and olfactory assessments. Self-reported olfactory impairment emerged as an independent predictor of dementia. After adjusting for effects of other predictors, individuals who rated their olfactory sensitivity as worse than normal were more likely to convert to dementia than those who reported normal olfactory sensitivity (odds ratio [OR] = 2.17; 95% confidence interval [CI] [1.40, 3.37]). Additionally, low scores on an odor identification test also predicted conversion to dementia (OR per 1 point increase = 0.89; 95% CI [0.81, 0.98]), but these two effects were additive. We suggest that assessing subjective olfactory complaints might supplement other assessments when evaluating the risk of conversion to dementia. Future studies should investigate which combination of olfactory assessments is most useful in predicting dementia conversion. (JINS, 2014, 20, 1-9)

Place, publisher, year, edition, pages
2014. Vol. 20, no 2, p. 209-217
Keyword [en]
Alzheimer type dementia, Awareness, Olfaction, Smell disorder, Memory, Vascular dementia
National Category
Psychology Neurosciences
Identifiers
URN: urn:nbn:se:su:diva-102990DOI: 10.1017/S1355617713001409ISI: 000332448700010OAI: oai:DiVA.org:su-102990DiVA, id: diva2:714220
Note

AuthorCount:6;

Available from: 2014-04-25 Created: 2014-04-25 Last updated: 2018-04-17Bibliographically approved
In thesis
1. Human olfaction: Associations with longitudinal assessment of episodic memory, dementia, and mortality risk
Open this publication in new window or tab >>Human olfaction: Associations with longitudinal assessment of episodic memory, dementia, and mortality risk
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: Department of Psychology, Stockholm University, 2018. p. 147
Keyword
olfaction, odor identification, self-assessments, aging, episodic memory, ApoE, dementia, Alzheimer’s disease, vascular dementia, mortality, cohort study, population-based.
National Category
Psychology
Research subject
Psychology
Identifiers
urn:nbn:se:su:diva-154414 (URN)978-91-7797-220-4 (ISBN)978-91-7797-221-1 (ISBN)
Public defence
2018-06-08, David Magnussonsalen (U31), Frescati Hagväg 8, Stockholm, 09:00 (English)
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Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.

Available from: 2018-05-16 Created: 2018-04-17 Last updated: 2018-05-09Bibliographically approved

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