Effects of Aging on Cerebral Morphology and Microstructure in Rhesus Macaques

Motivation: Neuroimaging studies, comparing young and old rhesus macaques, have revealed age-related morphological or microstructural brain changes. However, it is unclear at what stage of adult life these changes begin to emerge. Goal(s): To link morphological and microstructural brain changes within the same animals in a cross-sectional examination across the adult lifespan. Approach: High-resolution structural and diffusion brain images were collected from adult rhesus macaques across a wide age range. Voxel-wise analyses provided increased sensitivity to partial volume effects. Results: Age-related brain volumetric atrophy was localized to cortico-striatal regions, while age-associated changes in diffusion metrics were more widespread throughout white matter regions. Impact: Using a large age-diverse sample, we corroborate and extend previous findings of age-related brain changes in macaques, uncovering additional affected regions undetected with traditional imaging methods. This validates brain biomarkers in a translational animal model of normative human aging.