Age-Related Differences in Human Cortical Microstructure Depend on the Distance to the Nearest Vein

Age-related differences in cortical microstructure are used to understand the neuronal mechanisms that underlie human brain ageing. The cerebral vasculature contributes to cortical ageing, but its precise interaction with cortical microstructure is poorly understood. In a cross-sectional study, we combine venous imaging with vessel distance mapping (VDM) to investigate the interaction between venous distances and age-related differences in the microstructural architecture of the primary somatosensory cortex (S1), the primary motor cortex (M1), and additional areas in frontal cortex as non-sensorimotor control regions. We scanned 18 younger adults and 17 older adults using 7T-MRI to measure age-related changes in quantitative T1 (qT1) values, positive QSM (pQSM) values, and negative QSM (nQSM) values at 0.5 mm isotropic resolution. We modelled different cortical depths using an equi-volume approach and assessed the distance of each voxel to its nearest vein using VDM. Our data reveal a dependence of cortical qT1 and pQSM values on venous distance. In addition, there is an interaction between venous distance and age on qT1 values, driven by lower qT1 values in older compared to younger adults in voxels that are closer to a vein. Together, our data show that the local venous architecture explains a significant amount of variance in standard measures of cortical microstructure and should be considered in neurobiological models of human brain organisation and cortical ageing.