Gray and white matter reduction in hyposmic subjects--A voxel-based morphometry study

Area of Science:

• Neuroscience
• Neuroimaging
• Brain Anatomy

Background:

• Olfactory deprivation is known to cause structural brain remodeling, primarily affecting olfactory bulb and cortical areas.
• Previous research focused on complete olfactory loss (anosmia), with limited understanding of partial olfactory deficits (hyposmia).

Purpose of the Study:

• To investigate gray and white matter volume changes in individuals with hyposmia.
• To compare brain structure in hyposmic subjects versus a healthy control group.

Main Methods:

• Magnetic Resonance Imaging (MRI) on a 3T scanner was used for data acquisition.
• Voxel-Based Morphometry (VBM) analysis was conducted using VBM8 toolbox and SPM8 in Matlab.
• Age- and sex-matched control group was included for comparison.

Main Results:

• Significant gray matter volume loss was observed in the insular cortex, anterior cingulate cortex, orbitofrontal cortex, cerebellum, fusiform gyrus, precuneus, middle temporal gyrus, and piriform cortex.
• White matter volume loss was detected beneath the insular cortex, in the cerebellum, and middle frontal gyrus.
• White matter atrophy was spatially connected to gray matter loss, except in the middle frontal gyrus. No volume increases were found.

Conclusions:

• Hyposmia is associated with structural brain changes, including gray and white matter volume reduction.
• The observed pattern of gray matter alterations in hyposmia is similar to, but less extensive than, that seen in anosmia.
• This study provides the first report on white matter volume alterations in individuals with olfactory deficits.