Abstract
BackgroundCerebral metabolites are associated with different physiological processes in brain aging. Cortical and limbic structures play important roles in cognitive aging; however, the relationship between these structures and age remains unclear with respect to physiological underpinnings. Regional differences in metabolite levels may be related to different structural and cognitive changes in aging.MethodsMagnetic resonance imaging and spectroscopy were obtained from 117 cognitively healthy older adults. Limbic and other key structural volumes were measured. Concentrations of N-acetylaspartate (NAA) and choline-containing compounds (Cho) were measured in frontal and parietal regions. Neuropsychological testing was performed including measures of crystallized and fluid intelligence and memory.ResultsNAA in the frontal voxel was associated with limbic and cortical volumes, whereas Cho in parietal cortex was negatively associated with hippocampal and other regional volumes. Hippocampal volume was associated with forgetting, independent of age. Further, parietal Cho and hippocampal volume contributed independent variance to age corrected discrepancy between fluid and crystallized abilities.ConclusionThese findings suggest that physiological changes with age in the frontal and parietal cortices may be linked to structural changes in other connected brain regions. These changes are differentially associated with cognitive performance, suggesting potentially divergent mechanisms.
Highlights
Brain atrophy is well established in the context of normal aging
The magnetic resonance spectroscopy (MRS) indices along with covariates selected by the adaptive Least Absolute Shrinkage and Selection Operator (LASSO) regression for specific brain region of interest (ROI) volumes and the results from the subsequent multiple linear regression models are indicated in Tables 3, 4
The results suggest that relationships between concentration of cerebral metabolites and volumes exist in older adults even in the context of normal cognitive aging, and may reflect age-associated metabolic and neurophysiological alterations that affect the structure of the brain
Summary
Quantitative longitudinal analysis of brain volumes provides compelling evidence that regionally specific volume loss occurs with advancing age in most people (e.g., limbic and hippocampal regions; Lim et al, 1990). Functional imaging and cognitive testing corroborate these findings, showing changes in aging, in prefrontal and limbic brain regions (Grady et al, 2003; Rodriguez-Aranda and Sundet, 2006; Yin et al, 2016). Physiological relationships to these regional changes in structure are unclear. Understanding physiological relationships between these hierarchically linked structures may provide insight into the process of cognitive and brain aging. Regional differences in metabolite levels may be related to different structural and cognitive changes in aging
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