A Comprehensive Analysis of Connectivity and Aging Over the Adult Life Span

Aging has been associated with decreased intra- and internetwork connectivity during rest and task. Recent work has shown the influential role of the salience network over the default mode network (DMN) and executive control network (ECN). This study comprehensively investigates age-related changes in intra- and internetwork connectivity and effective connectivity between the DMN, ECN, and salience network across the adult life span. Two hundred ten participants completed a working memory task, an inhibition task, and a resting-state functional magnetic resonance imaging scan. Networks were extracted using independent component analysis; then, regression analyses and t-tests between three age groups, 21-40 (younger), 41-60 (middle), and 61-80 (older), were conducted. Older age was associated with decreased intranetwork connectivity. Functional network connectivity analyses revealed older age was associated with increased internetwork connectivity between the salience network and the ECNs and DMNs. In both cases, the effects were more pronounced in the tasks compared to resting state. Granger causality analyses indicated the salience network was influenced by the DMN and ECN in all age groups during both tasks, but not rest. However, middle adults showed increased influence from the salience network to the right ECN compared to younger adults during the flanker task. Taking everything into account, these findings indicate the role of the salience network changes over the life span, which may have implications for the early detection of pathophysiology in older adults.