Aging-related microstructural alterations along the length of the cingulum bundle

The aim of this study was to investigate the aging-related structural changes of the cingulum, one of the major components of the limbic network, which has a critical role in emotion, attention and memory. 35 healthy young adults (22.3 ± 2.7 years) and 33 healthy older adults (69.5 ± 3.5 years) were recruited. Diffusion weighted imaging data were acquired with a b-value = 2000 s/mm2, 61 diffusion directions and 4 non-weighted images. The fiber directions in each voxel were based on the constrained spherical deconvolution (CSD) model. The cingulum was segmented into three branches using deterministic tractography (subgenual, retrosplenial and parahippocampal), using a region-of-interest (ROI)-based approach. Atlas-based tractography (ABT) was the method used to obtain the output tracts of each branch of the cingulum. Along-tract analysis was performed on each branch. We found a statistically significant change with aging in the left subgenual branch of the cingulum with a decrease in fractional anisotropy (FA) and axial diffusivity (AD), as well as an increase in radial diffusivity (RD). No statistically significant differences were found between young and older groups in the other two branches. This study adds to knowledge about how the cingulum changes structurally along its entire length during aging in a more detailed way, thanks to an advanced methodological approach.