Within‐network Functional Connectivity of Intrinsic Networks in SuperAgers

Abstract Background Memory decline in late life is a hallmark of aging, yet SuperAgers are individuals age 80 or older with episodic memory performance at least as good as cognitively average 50‐to‐60‐year‐olds. Neuroimaging analyses have found SuperAgers to have thicker cortices and slower atrophy rates compared to similarly aged controls (Controls). This project extended the anatomical findings by examining the functional integrity of seven intrinsic networks spanning the entire cortex and two memory‐specific systems identified from task‐based and resting state studies. Methods Within‐network functional connectivity (FC) of seven large‐scale networks and two memory systems were compared between 25 SuperAgers and 16 Controls using resting state functional MRI (rs‐fMRI) and T 1 ‐weighted structural imaging from a single visit. Classification of SuperAgers/Controls was determined based on measures of episodic memory, executive functioning, verbal fluency, and picture naming (Harrison et al., 2012). Inclusion criteria required stable cognitive status across two visits. In the first analysis, we included all seven networks from a common resting‐state atlas (Schaefer et al., 2018). Within‐network FCs for all networks were defined as the average FCs between all within‐network regions (Figure 1A). In the second analysis, we investigated two memory‐specific networks: the anterior temporal (AT) and posterior medial (PM) systems. AT and PM cortical maps (Figure 1B) were identified from prior research (de Flores et al., 2022). Within‐network FC of the AT and PM systems were defined as the FC between AT‐to‐anterior‐hippocampus and PM‐to‐posterior‐hippocampus, respectively. For both analyses, FCs were compared across groups using two‐sample independent t ‐tests and corrected for multiple comparisons (Benjamini‐Hochberg false discovery rate). Results We found no significant between‐group differences in demographic characteristics including age, sex, and education. Performance on neuropsychological measures was significantly different for episodic memory, verbal fluency, and picture naming. Group differences in within‐network FCs for large‐scale networks and memory systems were nonsignificant. Conclusion At the group‐level, within‐network FC of large‐scale networks and memory‐specific systems were not a primary differentiator between cognitively average aging and SuperAging phenotypes. Person‐specific functional connectome approaches may be important for understanding network organizational features of SuperAgers.