Olfactory Bulb Volume Reflects Olfactory Dysfunction and Network Organization: Insights From the Population-Based...

Area of Science:

• Neuroscience
• Aging Research
• Olfactory System

Background:

• Olfactory dysfunction is prevalent in aging and early neurodegenerative diseases.
• The interplay between olfactory bulb (OB) volume and olfactory network (OFN) functional connectivity (FC) in odor identification is not well understood.
• Investigating these relationships can provide insights into aging and neurological conditions.

Purpose of the Study:

• To examine the associations between OB volume, OFN FC, and odor identification ability.
• To explore how these factors interact and influence olfactory function in a large population-based cohort.
• To identify potential biomarkers for olfactory dysfunction and neurodegeneration.

Main Methods:

• Utilized cross-sectional data from 5605 participants (aged 30-95 years) from the Rhineland Study.
• Extracted OB volume and OFN FC using 3T MRI scans.
• Assessed odor identification using the "Sniffin' Sticks" test and analyzed relationships with linear regression.

Main Results:

• Smaller OB volume correlated with poorer odor identification (β=0.09).
• This association was more pronounced in men and older individuals.
• Reduced OFN FC was linked to worse odor identification in individuals with large OBs, particularly older adults and in memory-related brain regions.

Conclusions:

• OB volume is crucial for detecting olfactory dysfunction.
• The OB influences odor identification directly and by modulating central network function.
• Olfactory dysfunction may serve as a potential biomarker for neurodegeneration.