Atlas55+: brain functional atlas of resting-state networks for late adulthood

The human brain is intrinsically organized into resting-state networks (RSNs). Currently, several human brain functional atlases are used to define the spatial constituents of these RSNs. However, the only brain functional atlases available are derived from samples of adults under the age of 40 years. As brain networks are continuously reconfigured throughout life, the lack of brain atlases derived from older populations may influence results related to the RSN properties in late adulthood. To address this, here we aimed to construct a reliable brain atlas derived from older healthy participants only. To do so, we analyzed the resting-state functional magnetic resonance imaging data from three large independent cohorts of healthy individuals in late life (total N=563; age range: 55-95 years) and a mid-life cohort (total N=322; age range: 18-54 years). Using a multi-step independent component analysis approach, we identified five major RSNs (default mode, salience, executive control, sensorimotor, and visual networks) across all the individuals in each cohort. We demonstrated: (a) high spatial reproducibility across the three late-life cohorts with an average spatial overlap of 67%, with the salience network having the lowest score (46%) and the visual network having the highest score (83%); and (b) RSNs derived from the late-life cohorts were spatially different from those derived from the mid-life cohort (p=0.016). In response, we constructed a novel brain functional atlas, called Atlas55+, which includes a consensus of the major RSNs across the three late-life cohorts. We show that the RSNs of Atlas55+: (1) did not show detectable differences between males and females, (2) showed spatial differences from those identified in younger healthy individuals, and (3) were independent of variation in neuroimaging parameters and sample composition. Atlas55+ provides the first reliable age-appropriate template for the major RSNs in late adulthood and is publicly available. Our results confirm the need to construct age-appropriate brain functional atlases for studies investigating brain mechanisms related to aging.

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