Exploring small‐world brain connectivity in aging and its relationship with cognitive reserve

INTRODUCTION: The aging brain's vulnerability to decline emphasizes the importance of strategies preserving cognitive function and independence. As age-related brain changes do not always match clinical symptoms, reserve, encompassing brain reserve (BR) and cognitive reserve (CR), has emerged as a key mechanism supporting resilience and mitigating cognitive decline during aging. This study adopts an exploratory approach to examine whether age- and CR-related differences are reflected in large-scale brain network organization, as assessed through electroencephalographic (EEG) connectivity metrics. METHODS: Resilience to age-related cognitive changes was investigated by relating CR, measured using the Cognitive Reserve Index (CRI), to brain network topology quantified by the Small-World (SW) index derived from resting-state EEG recordings. SW differences were first examined between age groups and then within each age group according to CRI levels, across EEG frequency bands (Delta, Theta, Alpha 1, Alpha 2, Beta 1, Beta 2, Gamma). RESULTS: The analysis of SW values showed distinct patterns between groups. Adults exhibited significant higher SW values in Delta and Theta bands, but lower values in Alpha 2 compared to Elderly. Within Elderly, higher CRI correlated with greater SW values in Delta, Beta 2, and Gamma bands, and marginally significant lower Alpha 2 values. DISCUSSION: Similar Mini-Mental State Examination (MMSE) scores across groups suggest these differences may reflect compensatory mechanisms, highlighting CR's potential role in preserving cognitive efficiency and resilience during aging. In line with the cognitive reserve framework, these findings provide supportive—though indirect—evidence that individual differences in CR are associated with distinct patterns of brain network organization during healthy aging. Overall, this study highlights the potential relevance of large-scale neural network dynamics as markers of adaptive brain functioning in later life, while underscoring the noncausal and exploratory nature of these associations.