Odor Identification Deficit Predicts Clinical Conversion from Mild Cognitive Impairment to Dementia Due to Alzheimer's Disease

Conti, Marta Zaffira; Vicini-Chilovi, Barbara; Riva, Maddalena; Zanetti, Marina; Liberini, Paolo; Padovani, Alessandro; Rozzini, Luca

doi:10.1093/arclin/act032

Cited by 122 publications

(82 citation statements)

References 43 publications

(39 reference statements)

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“…4 Deficits in OI precede impairment on olfactory threshold detection tasks 26 and remain after cognitive measures and odor detection deficits are controlled for, 5 suggesting a pathophysiologic process that originates near the central olfactory structures in the medial temporal lobe. 5,23,[27][28][29] Although the exact inception point of AD pathology in the olfactory system remains unknown, the disease course progressively involves 29 multiple levels of the olfactory system, 27,30 including peripheral structures such as the olfactory bulb and epithelium, as well as higher order olfactory pathways connected to cognitive processes. 25 Studies have shown greater OI deficits in patients with AD compared to those with vascular dementia, 31,32 suggesting that the site of vascular pathology may determine the type and severity of olfactory deficit, 33 with specific olfactory deficits observed only in patients whose corresponding olfactory structures sustained vascular damage, in contrast to the multiple-level impairment observed across the olfactory system in AD pathology.…”

Section: Resultsmentioning

confidence: 99%

Olfaction and risk of dementia in a biracial cohort of older adults

et al. 2017

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Objective: Prior studies indicate that olfactory function may be an early marker for cognitive impairment, but the body of evidence has been largely restricted to white populations. Methods:We studied 2,428 community-dwelling black and white older adults (baseline age 70-79 years) without dementia enrolled in the Health, Aging, and Body Composition (Health ABC) study. Olfaction was measured as odor identification (OI) with the 12-item Cross Cultural Smell Identification Test in year 3. We defined incident dementia over 12 years on the basis of hospitalization records, prescription for dementia medication, or 1.5-SD decline in race-stratified global cognition score. We assessed dementia risk associated with OI score (by tertile) using Cox proportional hazards models. All analyses were stratified by race.Results: Poorer OI in older adults without dementia was associated with increased risk of dementia. After adjustment for demographics, medical comorbidities, and lifestyle characteristics, white participants in the poor or moderate OI tertile had greater risk of dementia (adjusted hazard ratio [HR] 3.34, 95% confidence interval [CI] 2.45-4.54; and HR 1.84, 95% CI 1.33-2.54, respectively) compared to those in the good tertile of function. Among blacks, worse OI was associated with an increased risk of dementia, but the magnitude of the effect was weaker (p for interaction 5 0.04) for the poor OI tertile (adjusted HR 2.03, 95% CI 1.44-2.84) and for the moderate tertile (adjusted HR 1.42, 95% CI 0.97-2.10). There was no interaction between OI and APOE e4 and risk of dementia.Conclusions: While the magnitude of the association was stronger in whites, we found that poor OI was associated with increased risk of dementia among both black and white older adults. Olfactory testing may be a simple, inexpensive, and highly sensitive method of identifying older adults at risk for developing dementia, particularly when combined with other early markers.

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Section: Resultsmentioning

confidence: 99%

Olfaction and risk of dementia in a biracial cohort of older adults

et al. 2017

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“…In that study, in 88 patients with MCI, 47% of patients with low olfactory scores (,24) progressed to dementia in 2 years compared with 11% of patients with normal olfactory scores ($24). 29 The UPSIT and similar tests, with culturally appropriate modifications when needed, can be a useful predictor of cognitive decline and the transition to AD dementia across different ethnicities.…”

Section: Baseline Demographic and Clinical Measuresmentioning

confidence: 99%

Olfactory deficits predict cognitive decline and Alzheimer dementia in an urban community

et al. 2015

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Objective: To determine the predictive utility of baseline odor identification deficits for future cognitive decline and the diagnosis of Alzheimer disease (AD) dementia.Methods: In a multiethnic community cohort in North Manhattan, NY, 1,037 participants without dementia were evaluated with the 40-item University of Pennsylvania Smell Identification Test (UPSIT). In 757 participants, follow-up occurred at 2 years and 4 years.Results: In logistic regression analyses, lower baseline UPSIT scores were associated with cognitive decline (relative risk 1.067 per point interval; 95% confidence interval [CI] 1.040, 1.095; p , 0.0001), and remained significant (relative risk 1.065 per point interval; 95% CI 1.034, 1.095; p , 0.0001) after including covariates. UPSIT, but not Selective Reminding Test-total immediate recall, predicted cognitive decline in participants without baseline cognitive impairment. During follow-up, 101 participants transitioned to AD dementia. In discrete time survival analyses, lower baseline UPSIT scores were associated with transition to AD dementia (hazard ratio 1.099 per point interval; 95% CI 1.067, 1.131; p , 0.0001), and remained highly significant (hazard ratio 1.072 per point interval; 95% CI 1.036, 1.109; p , 0.0001) after including demographic, cognitive, and functional covariates.Conclusions: Impairment in odor identification was superior to deficits in verbal episodic memory in predicting cognitive decline in cognitively intact participants. The findings support the crosscultural use of a relatively inexpensive odor identification test as an early biomarker of cognitive decline and AD dementia. Such testing may have the potential to select/stratify patients in treatment trials of cognitively impaired patients or prevention trials in cognitively intact individuals.Neurology ® 2015;84:182-189 GLOSSARY AD 5 Alzheimer disease; AUC 5 area under the curve; CI 5 confidence interval; HR 5 hazard ratio; MCI 5 mild cognitive impairment; ROC 5 receiver operating characteristic; RR 5 relative risk; SRT 5 Selective Reminding Test; SRT-TR 5 Selective Reminding Test-total immediate recall; UPSIT 5 University of Pennsylvania Smell Identification Test; WHICAP 5 Washington Heights/Inwood Columbia Aging Project.

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“…In the present study, MMSE, which assessed cognitive function of the geriatric patients, showed significant positive correlation with discrimination and identification scores. As patients with severe cognitive dysfunction and Parkinson's disease are known to have olfactory dysfunction [18], and olfactory dysfunction could be an early symptom of neurodegenerative diseases such as Parkinson's disease and Alzheimer dementia [19], we excluded these patients from our study. Despite the exclusion of these patients, decreasing cognitive function scores correlated with decreasing discrimination and identification scores.…”

Section: Discussionmentioning

confidence: 99%