Reorganization of structural connectivity in the brain supports preservation of cognitive ability in healthy aging

Abstract

The global population is aging rapidly, and a research question of critical importance is why some older adults suffer tremendous cognitive decline while others are mostly spared. Past aging research has shown that older adults with spared cognitive ability have better local short-range information processing while global long-range processing is less efficient. We took this research a step further to investigate whether the underlying structural connections, measured in vivo using diffusion magnetic resonance imaging (dMRI), show a similar shift to support cognitive ability. We analyzed the structural connectivity streamline probability (representing the probability of connection between regions) and nodal efficiency and local efficiency regional graph theory metrics to determine if age and cognitive ability are related to structural network differences. We found that the relationship between structural connectivity and cognitive ability with age was nuanced, with some differences with age that were associated with poorer cognitive outcomes, but other reorganizations that were associated with spared cognitive ability. These changes included strengthened local intrahemispheric connectivity and increased nodal efficiency of the ventral occipital-temporal stream, nucleus accumbens, and hippocampus for older adults, and widespread local efficiency primarily for middle-aged individuals.

Dynamic network features of functional and structural brain networks support visual working memory in aging adults

“…Although age is commonly associated with declining cognitive ability, and negative brain changes, we have estimated complexity with multiscale entropy to demonstrate that some changes in the complexity of function activity with age are associated with spared cognitive ability (Heisz et al, 2015), and that different aspects of structural brain network reorganizations were associated with both declining as well as spared cognitive ability in older adults (Neudorf et al, 2024). In particular, increased local interhemispheric connections and specific regional differences in the organization of hub regions were associated with spared cognitive ability (Neudorf et al, 2024).…”

“…Adding a longitudinal perspective would represent an important contribution to this research investigating how the dynamic functional repertoires available are also dynamic across the lifespan, from infancy to childhood, adolescence, young adulthood, and old age. We know from both this and past research (Neudorf et al, 2024) that the network regimes that are ideal for healthy young adults are not the same as those that are ideal for older adults, so a continued exploration of brain networks across the lifespan with an eye for how these architectures address unique demands represents an important effort to diversify our understanding of how dynamic the brain network is across the lifespan.…”