Resting state network changes in aging and cognitive decline

Identifying the neural mechanisms related to aging in the lifespan represents a fundamental goal for clinical neuroscience. Here, we review recent advances in understanding the effects of aging on spontaneous brain activity and behavior. A large body of neuroimaging studies shows that spontaneous brain activity is intrinsically organized in large-scale resting-state networks (RSNs) associated with different cognitive functions such as memory, attention, language, and executive control. Furthermore, recent lines of evidence indicate that aging affects the patterns of correlated brain activity (functional connectivity) within and across RSNs. A common observation is that elderly individuals exhibit decreased functional connectivity within specific RSNs such as the default mode, dorsal attention and executive-control networks. Moreover, aging is associated with increased inter-network functional connectivity between RSNs, i.e. reduction of segregation between functional systems. Finally, some studies show that changes in functional connectivity are behaviorally relevant, i.e. they are correlated with a decline in cognitive abilities, mainly in memory and executive control functions. These findings strongly suggest that robust changes in RSNs occur in aging; hence investigations of spontaneous brain activity may shed light into brain processes related to aging or serve as a sensitive biomarker of cognitive decline and response to therapy.