| 1. |
- Hedner, Margareta, et al.
(författare)
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Age-Related Olfactory Decline is Associated with the BDNF Val66met Polymorphism : Evidence from a Population-Based Study
- 2010
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Ingår i: Frontiers in Aging Neuroscience. - : Frontiers Media SA. - 1663-4365. ; 2:7, s. 24-
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the effect of the brain-derived neurotrophic factor (BDNF) val66met polymorphism on change in olfactory function in a large scale, longitudinal population-based sample (n = 836). The subjects were tested on a 13 item force-choice odor identification test on two test occasions over a 5-year-interval. Sex, education, health-related factors, and semantic ability were controlled for in the statistical analyses. Results showed an interaction effect of age and BDNF val66met on olfactory change, such that the magnitude of olfactory decline in the older age cohort (70–90years old at baseline) was larger for the val homozygote carriers than for the met carriers. The older met carriers did not display larger age-related decline in olfactory function compared to the younger group. The BDNF val66met polymorphism did not affect the rate of decline in the younger age cohort (45–65years). The findings are discussed in the light of the proposed roles of BDNF in neural development and maintenance.
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| 2. |
- Olofsson, Jonas K., et al.
(författare)
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Long-term episodic memory decline is associated with olfactory deficits only in carriers of ApoE-є4
- 2016
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Ingår i: Neuropsychologia. - : Elsevier BV. - 0028-3932 .- 1873-3514. ; 85, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The ɛ4 allele of the Apolipoprotein E gene is a genetic risk factor for late-onset dementia of the Alzheimers' type (DAT), which is characterized by loss of both episodic memoryand olfactory functions. Little is known about the possible role of ɛ4 in the association between ongoing episodic memory decline and olfactory deficits in the general population, but such information is relevant in determining the relevance of olfaction as a marker of DAT risk. The present study was based on a large, population-based sample (n=1087, aged 45–90 years, of which 324 were ɛ4-carriers). Episodic memory change rates were established using data collected every 5 years for a 10–20 year interval leading up to an olfactory assessment using the Scandinavian Odor Identification Test at the last wave of data collection. Participants were classified according to whether or not their episodic memory ability declined more rapidly than the age-typical norm (by >1SD). Our main result is that only in ɛ4-carriers was episodic memory decline associated with odor identification impairment. In individuals without ɛ4, odor identification was unrelated to episodic memory decline status. Follow-up analyses indicated that this moderation by ɛ4 was due to the olfactory nature of the identification test, and that the effect was not caused by 63 individuals with dementia. Our results suggest that the ɛ4 determines the functional association between ongoing episodic memory decline and olfaction. These findings are consistent with the notion that ɛ4-carriers with DAT, compared to non-carriers, display a cortical atrophy pattern that is more focused on mediotemporal lobe regions supporting olfactory and episodic memory functions. Olfactory and memory assessments might provide complementary information on mediotemporal atrophy prior to clinical dementia onset, but the ɛ4 should be considered when using olfactory assessment as an early-stage indicator.
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| 3. |
- Olofsson, Jonas K., et al.
(författare)
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Odor Identification Deficit as a Predictor of Five-Year Global Cognitive Change : Interactive Effects with Age and ApoE-ε4
- 2009
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Ingår i: Behavior Genetics. - : Springer Netherlands. - 0001-8244 .- 1573-3297. ; 39:5, s. 496-503
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Tidskriftsartikel (refereegranskat)abstract
- Olfactory impairments are present in common neurodegenerative disorders and predict conversion to dementia in non-demented individuals with cognitive impairment. In cognitively intact elderly, evidence is sparse regarding the role of olfactory deficits in predicting cognitive impairment. The present study investigated predictors of 5-year prospective decline in the Mini-Mental State Examination (MMSE) in a large (n = 501), population-based sample of elderly (65–90 years) individuals. All participants were genotyped for the ApoE gene, assessed for health factors, and were non-demented at the baseline assessment. After partialling out the influences of demographic and health-factors at baseline and dementia at follow-up, poor odor identification ability in combination with older age and the ApoE-ε4 allele predicted larger prospective global cognitive decline. This effect could not be produced by a vocabulary test. In sum, the findings suggest that an olfactory deficit can dissociate between benign and malign global cognitive development in non-demented, very old ε4-carriers, who are at high risk of developing dementia.
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| 4. |
- Ekström, Ingrid, et al.
(författare)
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Smell Loss Predicts Mortality Risk Regardless of Dementia Conversion
- 2017
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 65:6, s. 1238-1243
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesTo determine whether dementia could explain the association between poor olfactory performance and mortality risk within a decade-long follow-up period.DesignProspective cohort study.SettingBetula Study, Umeå, Sweden.ParticipantsA population-based sample of adult participants without dementia at baseline aged 40 to 90 (N = 1,774).MeasurementsOlfactory performance using the Scandinavian Odor-Identification Test (SOIT) and self-reported olfactory function; several social, cognitive, and medical risk factors at baseline; and incident dementia during the following decade.ResultsWithin the 10-year follow-up, 411 of 1,774 (23.2%) participants had died. In a Cox model, the association between higher SOIT score and lower mortality was significant (hazard ratio (HR) = 0.74 per point interval, 95% confidence interval (CI) = 0.71-0.77, P < .001). The effect was attenuated, but remained significant, after controlling for age, sex, education, and health-related and cognitive variables (HR = 0.92, 95% CI = 0.87-0.97, P = .001). The association between SOIT score and mortality was retained after controlling for dementia conversion before death (HR = 0.92, 95% CI = 0.87-0.97, P = .001). Similar results were obtained for self-reported olfactory dysfunction.ConclusionPoor odor identification and poor self-reported olfactory function are associated with greater likelihood of future mortality. Dementia does not attenuate the association between olfactory loss and mortality, suggesting that olfactory loss might mark deteriorating health, irrespective of dementia.
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| 5. |
- Kubik, Veit, et al.
(författare)
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Effects of testing on subsequent re-encoding and long-term forgetting of action-relevant materials : On the influence of recall type
- 2015
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Ingår i: Scandinavian Journal of Psychology. - : Wiley. - 0036-5564 .- 1467-9450. ; 56:5, s. 475-481
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Tidskriftsartikel (refereegranskat)abstract
- Testing one's memory of previously studied information reduces the rate of forgetting, compared to restudy. However, little is known about how this direct testing effect applies to action phrases (e.g., wash the car) - a learning material relevant to everyday memory. As action phrases consist of two different components, a verb (e.g., wash) and a noun (e.g., car), testing can either be implemented as noun-cued recall of verbs or verb-cued recall of nouns, which may differently affect later memory performance. In the present study, we investigated the effect of testing for these two recall types, using verbally encoded action phrases as learning materials. Results showed that repeated study-test practice, compared to repeated study-restudy practice, decreased the forgetting rate across 1 week to a similar degree for both noun-cued and verb-cued recall types. However, noun-cued recall of verbs initiated more new subsequent learning during the first restudy, compared to verb-cued recall of nouns. The study provides evidence that testing has benefits on both subsequent restudy and long-term retention of action-relevant materials, but that these benefits are differently expressed with testing via noun-cued versus verb-cued recall.
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| 6. |
- Kubik, Veit, et al.
(författare)
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Putting action memory to the test : Testing affects subsequent restudy but not long-term forgetting of action events
- 2016
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Ingår i: Journal of Cognitive Psychology. - : Informa UK Limited. - 2044-5911 .- 2044-592X. ; 28:2, s. 209-219
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Tidskriftsartikel (refereegranskat)abstract
- Testing memory typically enhances subsequent re-encoding of information (“indirect” testing effect) and, as compared to restudy, it also benefits later long-term retention (“direct” testing effect). We investigated the effect of testing on subsequent restudy and 1-week retention of action events (e.g. “water the plant”). In addition, we investigated if the type of recall practice (noun-cued vs. verb-cued) moderates these testing benefits. The results showed an indirect testing effect that increased following noun-cued recall of verbs as compared to verb-cued recall of nouns. In contrast, a direct testing effect on the forgetting rate of performed actions was not reliably observed, neither for noun- nor verb-cued recall. Thus, to the extent that this study successfully dissociated direct and indirect testing-based enhancements, they seem to be differentially effective for performed actions, and may rely on partially different mechanisms.
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| 7. |
- Larsson, Maria, et al.
(författare)
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Loss of Olfactory Function Predicts Mortality Irrespective of Dementia Conversion : 10-year follow-up of an age-varied sample
- 2016
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Ingår i: Chemical Senses. - : Oxford University Press (OUP). - 0379-864X .- 1464-3553. ; 41:9, s. e111-e288
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to examine the association between performance in odor identification and future mortality in a community cohort of adults aged between 40 and 90 years. We assessed olfactory performance with a 13-item-version of the Scandinavian Odor Identification Test (SOIT). The results showed that during follow-up (mean=9.4 years, standard deviation=2.23), 411 of 1774 (23.2%) participants died. In a Cox model, the association between higher SOIT score and mortality was highly significant (hazard ratio [HR]=0.74, per point interval, 95% confidence interval [CI]=0.71–0.77, p<0.001). The effect was attenuated, but remained significant after controlling for age, sex, education, and health and cognitive variables that were also associated with an increased risk of mortality (HR=0.92, 95% CI=0.87–0.97, p=0.001). Controlling for dementia conversion prior to death did not attenuate the association between SOIT score and mortality (HR=0.92, 95% CI=0.87–0.97, p=0.001). Similar results were obtained for olfactory sensitivity as assessed by self-report. Overall, the present findings show that poor odor identification performance is associated with an increased likelihood of future mortality in middle-aged and older adults, after controlling for social, cognitive, and medical risk factors. Most importantly, controlling for the development of dementia did not attenuate the association between odor identification and mortality, suggesting that olfactory decline might mark deteriorating health also irrespective of dementia.
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| 8. |
- Olofsson, Jonas K, 1965-, et al.
(författare)
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Odor identification impairment in carriers of ApoE-ε4 is independent of clinical dementia
- 2010
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Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 31:4, s. 567-577
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Tidskriftsartikel (refereegranskat)abstract
- The ApoE gene is expressed in olfactory brain structures and is believed to play a role in neuronal regenerative processes as well as in development of Alzheimer's disease (AD), the most common form of dementia. The ε4 allele has been reported to be associated with compromised odor identification ability in the elderly, and this deficit has been interpreted as a sign of pre-diagnostic AD. However, because it has not been demonstrated that the relationship between the ε4 allele and odor identification is mediated by dementia, it is possible that the ε4 allele may have an effect on odor identification over and above any effects of dementia. The present study investigated effects of ApoE-status on odor identification in a large, population-based sample (n = 1236) of adults (45–80 years), who were assessed for dementia at time of testing and 5 years later. The results showed that the ε4 allele was associated with an odor identification deficit among elderly participants (75–80). Critically, this effect remained after current and pre-diagnostic dementia, vocabulary, global cognitive status and health variables were partialled out. The present results suggest that the ApoE gene plays a role in olfactory functioning that is independent of dementia conversion within 5 years.
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| 9. |
- Stanciu, Ingrid, et al.
(författare)
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Olfactory Impairment and Subjective Olfactory Complaints Independently Predict Conversion to Dementia : A Longitudinal, Population-Based Study
- 2014
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Ingår i: Journal of the International Neuropsychological Society. - 1355-6177 .- 1469-7661. ; 20:2, s. 209-217
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Tidskriftsartikel (refereegranskat)abstract
- 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)
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| 10. |
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