Olfactory impairment in mild cognitive impairment with Lewy bodies and Alzheimer’s disease
Thomas, AJ; Hamilton, CA; Barker, S; et al.Durcan, R; Lawley, S; Barnett, N; Firbank, M; Roberts, G; Allan, LM; O'Brien, J; Taylor, JP; Donaghy, PC
Date: 20 October 2021
Article
Journal
International Psychogeriatrics
Publisher
Cambridge University Press / International Psychogeriatric Association
Publisher DOI
Abstract
Objectives:
Impaired olfaction may be a biomarker for early Lewy body disease but its value in Mild
Cognitive Impairment with Lewy bodies (MCI-LB) is unknown. We compared olfaction in
MCI-LB with MCI due to Alzheimer’s disease (MCI-AD) and healthy older adults. We
hypothesised that olfactory function would be worse in probable ...
Objectives:
Impaired olfaction may be a biomarker for early Lewy body disease but its value in Mild
Cognitive Impairment with Lewy bodies (MCI-LB) is unknown. We compared olfaction in
MCI-LB with MCI due to Alzheimer’s disease (MCI-AD) and healthy older adults. We
hypothesised that olfactory function would be worse in probable MCI-LB than in both MCI-
AD and healthy comparison subjects (HC).
Design:
Cross-sectional study assessing olfaction using Sniffin’ Sticks 16 (SS-16) in MCI-LB, MCI-
AD and HC with longitudinal follow-up. Differences were adjusted for age and receiver
operating characteristic curves were used for discriminating MCI-LB from MCI-AD andHC.
Setting:
Participants were recruited from Memory Services in the North East of England
Participants:
38 probable MCI-LB, 33 MCI-AD, 19 possible MCI-LB and 32HC.
Measurements:
Olfaction was assessed using SS-16 and a questionnaire.
Results:
Participants with probable MCI-LB had worse olfaction than both MCI-AD (Age-adjusted
mean difference (B)=2.05,95% CI:0.62-3.49, p=.005) and HC (B=3.96, 95% CI:2.51–5.40,
p<.001). The previously-identified cut-off score for the SS-16 of ≤ 10 had 84% sensitivity for
probable MCI-LB (95% CI: 69-94%) but 30% specificity vs MCI-AD. ROC analysis found a
lower cut-off of ≤ 7 was better (63% sensitivity for MCI-LB, with 73% specificity vs MCI-AD
and 97% vsHC). Asking about olfactory impairments was not useful in identifying them.
Conclusions:
MCI-LB had worse olfaction than MCI-AD and normal ageing. A lower cut-off score of ≤ 7 is
required when using SS-16 in such patients. Olfactory testing may have value in identifying
early LB disease in memory services.
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