The senescent encephalon: A morphometric and functional study of normal brain aging

SOFÍA ABREVAYA; MARTÍN DOTTORI; LUCAS SEDEÑO; SOL FITTIPALDI; ADOLFO M. GARCÍA; INDIRA GARCÍA-CORDERO; MALIN HILDEBRANT; AGUSTIN IBÁÑEZ

Congreso; Society for Neuroscience; 2018

As humans age, their neurological systems normally manifest structural and functional alterations, accompanied by cognitive decline. In order to characterize such mechanisms, we aimed to identify those structures and networks which feature major changes as individuals grow old. We obtained structural and functional magnetic resonance images from 136 healthy subjects, ranging from age 17 to 84. Gray matter (GM) atrophy was evaluated via voxel-based morphometry (VBM). First, we assessed the association between GM volume and aging through non-parametric correlations. Then, we compared GM differences between three samples separated by age: young adults (YAs, 17-35), adults (As, 31-59), and seniors (Ss, 60-84). Functional connectivity (FC) changes were evaluated with the network-based statistic (NBS) toolbox. A whole-group analysis at the lobule level revealed that aging was associated with reduced GM in the frontal, temporal, thalamic, and occipital areas. At the voxel-level, this relationship was observed specifically in the caudate, hippocampus, supramarginal, middle cingulate, thalamus, lingual and cerebellum regions.The group comparison revealed differences between YAs and As in the same areas as the whole-group correlation between GM and age, but only frontal differences were found between As and Ss. Regarding FC, the whole-group analysis yielded a negative association between age and frontal connectivity. However, in the between-group analyses, As presented lesser connectivity than YAs only between parietal and cerebellar areas, whereas connectivity alterations for Ss relative to As were confined to posterior areas. Taken together, our findings suggest that age-related structural and functional brain changes are maximal in the transition from young adulthood into adulthood, and less marked towards seniority, when structural loss is more anterior, but connectivity differences are mainly posterior. In this way, our study provides new insights on the neurobiological correlates of healthy aging.