Correlation between baseline regional gray matter volume and global gray matter volume decline rate

Evaluating whole-brain or global gray matter volume decline rate is important in distinguishing neurodegenerative diseases from normal aging and in anticipating cognitive decline over a given period in non-demented subjects. Whether a significant negative correlation exists between baseline regional gray matter volume of several regions and global gray matter volume decline in the subsequent time period in healthy subjects has not yet been clarified. Therefore, we analyzed the correlation between baseline regional gray matter volumes and the rate of global gray matter volume decline in the period following baseline using magnetic resonance images of the brains of 381 healthy subjects by applying a longitudinal design over 6 years using voxel-based morphometry. As a result, the annual percentage change in gray matter ratio (GMR, APC(GMR)), in which GMR represents the percentage of gray matter volume in the intracranial volume, showed a significant negative correlation with the baseline regional gray matter volumes of the right posterior cingulate cortex/precuneus and the left hippocampus. Additionally, baseline regional gray matter volume of both the right PCC/precuneus and the left hippocampus significantly distinguished whether the APC(GMR) was above or below the mean of APC(GMR). Our results suggest that baseline regional gray matter volume predicts the rate of global gray matter volume decline in the subsequent period in healthy subjects. Our study may contribute to distinguishing neurodegenerative diseases from normal aging and to predicting cognitive decline.