Högskolan i Skövde

Background: Cognitive aging demonstrates substantial interindividual variability, with some individuals maintaining high cognitive performance despite advancing age. This study examines the relationships between white matter microstructure, sleep duration, neuroinflammation, and working memory performance in healthy aging within the brain maintenance theoretical framework.

Methods: 39 participants underwent multimodal neuroimaging, including neurite orientation dispersion and density imaging (NODDI) to assess white matter microstructure and PET to quantify neuroinflammation. Self-reported sleep duration was recorded, and working memory was assessed through standardized cognitive testing. Regions of interest were key white matter tracts including the superior longitudinal fasciculus, corpus callosum, frontal aslant tract, and corona radiata.

Results: Contrary to hypotheses, higher neurite density index (NDI) in the genu of the corpus callosum correlated with lower working memory scores. Sleep duration showed no significant association with working memory, and its positive correlation with orientation dispersion index (ODI) in the left anterior corona radiata did not survive multiple comparisons correction. No robust associations were observed between neuroinflammation and either WM microstructure or working memory, and exploratory PET findings suggested an unexpected negative association with age.

Conclusions: These findings challenge assumptions about the protective roles of sleep and low inflammation for white matter integrity and cognition in aging. Limited by sample size, the inconclusive results underscore the complexity of brain aging and highlight the need for longitudinal, multimodal approaches to understand the mechanisms underlying cognitive resilience in later life.