Aging effects on functional connectivity within and between resting-state networks

It is well known that aging is related to cognitive decline. Recently, imaging studies of resting-state have reported that some brain networks, which reflect synchronization of spontaneous activities, are disrupted by aging. However, most studies have focused on the default mode network consisting of medial prefrontal cortex, posterior cingulate cortex, and inferior parietal lobe, and ignored other resting-state networks. In this study, we measured the resting-state activity using functional magnetic resonance imaging, and explored whether cognitive decline with aging is related to disrupted resting-state networks. We applied independent component analysis for evaluation of the functional connectivity. Degree of gray matter atrophy was controlled as nuisance covariate. As a result, the connectivity of the salience network consisting of bilateral insula and anterior cingulated cortex was notably decreased with aging, and the decreased functional connectivity was correlated with the measures of individual cognitive ability. Furthermore, some internetwork connectivities were also decreased with aging. These results suggest that aging affects not only the default mode network but also other networks, specifically the salience network and inter-network connectivity, and that disruption of the salience network is related to cognitive decline in elderly people.