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Updated: Feb 17, 2026
A Free-breathing fMRI Method to Study Human Olfactory Function
Published on: July 30, 2017
Change of olfactory function as a marker of inflammatory activity and disability progression in MS
Gabriel Bsteh1, Harald Hegen1, Felix Ladstätter1
1Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria.
Background:
Impaired olfactory threshold has been reported in early inflammatory phases of MS, while impaired odor identification was associated with more widespread disability.
Objective:
To prospectively assess the development of olfactory function and its correlation with relapse and disability progression.
Methods:
In this prospective, 3-year longitudinal study on 151 MS patients and 30 healthy controls, three different qualities of olfactory function (threshold, discrimination, and identification) were quantified using the Sniffin' Sticks test. The influence of relapses and disability on olfactory function was analyzed at different time points and in a multivariate model.
Results:
Discrimination and identification capability significantly worsened over 3 years, while threshold did not. Threshold was markedly impaired in patients with relapse activity within 12 months, recovered in the absence of relapse, and was associated with a 2.5-fold increased risk of relapse. Deterioration of discrimination and identification was irreversible and both strongly associated with and predictive of EDSS progression.
Conclusion:
Olfactory function changes over time in MS. Threshold impairment is transient and predicts inflammatory disease activity, while odor identification and discrimination are associated with disability progression. Olfactory dysfunction might be a useful and easily obtainable parameter to monitor patients with regard to inflammation and neurodegeneration in MS.
Insights
Olfactory threshold impairment in multiple sclerosis (MS) predicts relapses, while odor identification and discrimination decline predict disability progression. These olfactory changes may help monitor MS progression.
Area of Science:
- Neurology
- Neuroscience
- Olfactory Research
Background:
- Olfactory threshold impairment is noted in early multiple sclerosis (MS) inflammatory phases.
- Impaired odor identification correlates with advanced disability in MS patients.
Purpose of the Study:
- To prospectively evaluate olfactory function changes over three years in MS patients.
- To correlate olfactory function (threshold, discrimination, identification) with relapse and disability progression.
Main Methods:
- A 3-year longitudinal study involving 151 MS patients and 30 controls.
- Olfactory function assessed using the Sniffin' Sticks test (threshold, discrimination, identification).
- Analysis of relapse and disability (EDSS) influence on olfactory function.
Main Results:
- Odor discrimination and identification significantly worsened over 3 years; threshold did not.
- Threshold impairment was linked to recent relapse activity and predicted future relapses.
- Deterioration in discrimination and identification was irreversible and predicted EDSS progression.
Conclusions:
- Olfactory threshold changes in MS are transient and indicate inflammatory activity.
- Declining odor identification and discrimination correlate with and predict disability progression in MS.
- Olfactory dysfunction serves as a valuable, accessible biomarker for monitoring MS inflammation and neurodegeneration.
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