Correlation between regional brain volume and olfactory function in very mild amnestic patients

Area of Science:

• Neuroscience
• Neuroimaging
• Olfactory Function

Background:

• Mild cognitive impairment (MCI) and early Alzheimer's disease (AD) often present with subtle cognitive changes.
• Olfactory dysfunction can be an early indicator of neurodegenerative processes.

Purpose of the Study:

• To identify the neural correlates of olfactory detection and identification in patients with very mild amnestic conditions.
• To investigate the relationship between cognitive function and olfactory abilities in this population.

Main Methods:

• Seventy patients with MCI or AD (Clinical Dementia Rating 0.5) underwent T&T olfactometry for olfactory assessment.
• Voxel-wise correlation analysis examined gray matter volume in relation to olfactometry scores.
• Neuropsychological test results were correlated with olfactory performance.

Main Results:

• Olfactory detection scores negatively correlated with nucleus accumbens and left parahippocampal gyrus volumes.
• Olfactory identification scores showed negative correlations with orbitofrontal, right frontal, and right anterior temporal cortex volumes.
• Olfactory identification scores were significantly associated with word recall in the Alzheimer's Disease Assessment Scale-Cognitive Part.

Conclusions:

• Olfactory detection deficits in MCI/early AD are linked to the olfactory circuit, while identification impairments involve neocortical regions.
• Olfactory identification dysfunction is associated with episodic memory deficits in patients with very mild amnestic syndromes.