Relationship between hippocampal subfields volume and balance function in healthy older adults

･A correlation between balance function and the volume of the hippocampus and subfields was found in healthy elderly subjects.
･The balance function may be involved in the volume of the whole hippocampus and specific subfields. The index of postural stability (IPS) closed eyes/soft surface condition is considered to reflect vestibular function.
･Thus, IPS may be useful in evaluations of the relationship between the vestibular system function via the hippocampus and balance.

Abstract

The volume of the hippocampus and its subfields is known to be affected by aging, disease, and physical training. In regard to training, the differential effects of aerobic exercise and dance training on the subfield volume suggest that balance function may be involved. However, the relationship between balance function and the volume of the hippocampus and its subfields remains unclear. Subjects were 30 cognitively intact individuals. They underwent balance tests, cognitive tests and structural MRI scans. The balance index measured was IPS under a visual block condition and/or a proprioception block condition. MR images acquired using a 3-tesla system and three-dimensional T1-weighted images were segmented in the hippocampal subfield with Freesurfer 6.0.0. The relationship between the IPS and hippocampal volume was evaluated. A positive correlation was observed only between the IPS closed eyes/soft surface condition and whole hippocampal volume ratio. In the subfields, positive correlations were found between the IPS and molecular layer of the hippocampus, granule cell layer of the dentate gyrus (GC-ML-DG), and cornu ammonis areas (CA)3 and CA4. These correlations were stronger under the closed eyes/soft surface condition than under the other conditions.

Benefit

This is the first study to examine the correlation between hippocampus subfields and balance function in healthy elderly subjects, providing novel important insights into the association between balance function and hippocampus. In healthy elderly subjects, the results of this study reveal that the better the balance function related to the vestibular system, the larger the volume of the whole hippocampus and specific subfields.

Market Application

The findings of this study suggest that the IPS may be useful for evaluating the relationship between vestibular system function via the hippocampus and balance in dementia.