Markers of olfactory dysfunction and progression to dementia: A 12‐year population‐based study

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 populationbased 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. ε4/ε4: 19.84;.Discussion: OD is associated with increased risk of dementia, especially severe impairment in combination with genetic risk of Alzheimer's disease.

Odor Identification Across Time in Mutation Carriers and Non-Carriers in Autosomal-Dominant Alzheimer’s Disease

“…The present results showing a difference in olfactory function in MC versus NC in adAD correspond with results in previous research in sAD and MCI showing impaired olfactory function [1,[6][7][8][39][40]. The present results in NC from adAD families cor-respond with results in previous research showing some decline in normal aging too, although less pronounced than the decline in AD [1,3,7,8].…”

“…The total identification score was the summarized score of free and cued identification divided by the total number of odors presented. Anosmia, hyposmia, and normosmia were defined based on the total identification score [37][38][39][40].…”

“…The results on free and total odor identification for MC and NC groups with p-values and effect size (Cohen's d) are presented in anosmic according to common criteria for total odor identification [36][37][38][39], while no NC individual was anosmic. In contrast, 18 NC were evaluated as normal in total odor identification, while 12 MC individuals performed normally in odor identification.…”

Trajectories of olfactory identification preceding incident mild cognitive impairment and dementia: a longitudinal study

“…Previous cross-sectional and longitudinal studies have reported increased dementia risk 8 , 10 , 33 , 34 and accelerated progression from MCI to dementia 6 , 11 in those with poorer olfactory identification. We similarly found that, among participants with incident MCI, olfactory identification declined faster for those who went on to develop dementia compared to those who did not.…”

“…Olfactory dysfunction has been identified as a predictor of MCI 4 , 5 , 6 , 7 and dementia, 8 , 9 , 10 and has been associated with accelerated progression from MCI to dementia. 6 , 11 Brain areas involved in olfaction, such as the entorhinal cortex and hippocampus, 12 appear to be the first impacted by Alzheimer’s disease (AD) pathologies.…”