Subtle Gray Matter Changes in Temporo-Parietal Cortex Associated with Cardiovascular Risk Factors

Abstract

Vascular risk factors may play an important role in the pathophysiology of Alzheimer's disease (AD). While there is consistent evidence of gray matter (GM) abnormalities in earlier stages of AD, the presence of more subtle GM changes associated with vascular risk factors in the absence of clinically significant vascular events has been scarcely investigated. This study aimed to examine GM changes in elderly subjects with cardiovascular risk factors. We predicted that the presence of cardiovascular risk would be associated with GM abnormalities involving the temporal-parietal cortices and limbic structures. We recruited 248 dementia-free subjects, age range 66-75 years, from the population-based "Sao Paulo Ageing and Health Study", classified in accordance to their Framingham Coronary Heart Disease Risk (FCHDR) score to undergo an MRI scan. We performed an overall analysis of covariance, controlled to total GM and APOE4 status, to investigate the presence of regional GM abnormalities in association with FCHDR subgroups (high-risk, medium-risk, and low-risk), and followed by post hoc t-test. We also applied a co-relational design in order to investigate the presence of linear progression of the GM vulnerability in association with cardiovascular risk factor. Voxel-based morphometry showed that the presence of cardiovascular risk factors were associated with regional GM loss involving the temporal cortices bilaterally. Those results retained statistical significance after including APOE4 as a covariate of interest. We also observed that there was a negative correlation between FCHDR scores and rGM distribution in the parietal cortex. Subclinical cerebrovascular abnormalities involving GM loss may provide an important link between cardiovascular risk factors and AD.