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Olfactory evaluation in Mild Cognitive Impairment: correlation with neurocognitive performance and endothelial
Alessandro Tonacci1, Rosa M Bruno1,2, Lorenzo Ghiadoni2
1Clinical Physiology Institute - National Research Council (IFC-CNR), Via Moruzzi 1, 56124, Pisa, Italy.
Abstract:
Mild Cognitive Impairment (MCI) is an intermediate condition between normal aging and dementia, associated with an increased risk of progression into the latter within months or years. Olfactory impairment, a well-known biomarker for neurodegeneration, might be present in the condition early, possibly representing a signal for future pathological onset. Our study aimed at evaluating olfactory function in MCI and healthy controls in relation to neurocognitive performance and endothelial function. A total of 85 individuals with MCI and 41 healthy controls, matched for age and gender, were recruited. Olfactory function was assessed by Sniffin' Sticks Extended Test (Burghart, Medizintechnik, GmbH, Wedel, Germany). A comprehensive neurocognitive assessment was performed. Endothelial function was assessed by flow-mediated dilation (FMD) of the brachial artery by ultrasound. MCI individuals showed an impaired olfactory function compared to controls. The overall olfactory score is able to predict MCI with a good sensitivity and specificity (70.3 and 77.4% respectively). In MCI, olfactory identification score is correlated with a number of neurocognitive abilities, including overall cognitive status, dementia rating, immediate and delayed memory, visuospatial ability and verbal fluency. FMD was reduced in MCI (2.90 ± 2.15 vs. 3.66 ± 1.96%, P = 0.016) and was positively associated with olfactory identification score (ρs =0.219, P = 0.025). The association remained significant after controlling for age, gender, and smoking. In conclusion, olfactory evaluation is able to discriminate between MCI and healthy individuals. Systemic vascular dysfunction might be involved, at least indirectly, in olfactory dysfunction in MCI.
Insights
Olfactory impairment is a key indicator of Mild Cognitive Impairment (MCI), predicting its onset and correlating with cognitive decline. Vascular dysfunction may also play a role in this olfactory deficit.
Area of Science:
- Neurology
- Gerontology
- Neuroscience
Background:
- Mild Cognitive Impairment (MCI) represents a transitional stage between normal aging and dementia.
- Olfactory impairment is an early biomarker for neurodegeneration, potentially signaling future pathological changes.
- Understanding olfactory function in MCI is crucial for early detection and intervention.
Purpose of the Study:
- To evaluate olfactory function in individuals with MCI compared to healthy controls.
- To investigate the relationship between olfactory function, neurocognitive performance, and endothelial function in MCI.
- To determine if olfactory scores can predict MCI and correlate with cognitive abilities and vascular health.
Main Methods:
- Recruited 85 individuals with MCI and 41 healthy controls, matched for age and gender.
- Assessed olfactory function using the Sniffin' Sticks Extended Test.
- Performed comprehensive neurocognitive assessments and measured endothelial function via flow-mediated dilation (FMD).
Main Results:
- Individuals with MCI exhibited significantly impaired olfactory function compared to controls.
- The overall olfactory score demonstrated good sensitivity (70.3%) and specificity (77.4%) in predicting MCI.
- In MCI patients, olfactory identification scores correlated with various cognitive functions, including memory and verbal fluency.
- Reduced FMD was observed in MCI, and it was positively associated with olfactory identification, even after controlling for confounding factors.
Conclusions:
- Olfactory evaluation effectively distinguishes individuals with MCI from healthy controls.
- Olfactory dysfunction in MCI is linked to neurocognitive deficits and potentially influenced by systemic vascular dysfunction.
- Olfactory testing offers a valuable, non-invasive tool for assessing MCI and its associated pathologies.