Preserved functional connectivity in the default mode and salience networks is associated with youthful memory in superaging

Abstract

'Superagers' are older adults who, despite their advanced age, maintain youthful memory. Previous morphometry studies revealed multiple default mode network (DMN) and salience network (SN) regions whose cortical thickness is preserved in superagers and correlates with memory performance. In this study, we examined the intrinsic functional connectivity within DMN and SN in 41 young (24.5 {+/-} 3.6 years old) and 40 elderly adults (66.9 {+/-} 5.5 years old). As in prior studies, superaging was defined as youthful performance on a memory recall task, the California Verbal Learning Test (CVLT). Participants underwent a resting state fMRI scan and performed a separate visual-verbal recognition memory task. As predicted, within both DMN and SN, superagers had stronger connectivity compared to typical older adults and similar connectivity compared to young adults. Superagers also performed similarly to young adults and better than typical older adults on the recognition task, demonstrating youthful episodic memory that generalized across memory tasks. Stronger connectivity within each network independently predicted better performance on both the CVLT and recognition task in older adults. Variation in intrinsic connectivity explained unique variance in memory performance, above and beyond preserved neuroanatomy. A post-hoc analysis revealed that DMN and SN nodes were more strongly inversely correlated in superagers than in typical older adults but were similarly correlated in superagers and young adults. Stronger between-network inverse correlations also predicted better memory performance in the entire sample of older adults. These results extend our understanding of the neural basis of superaging as a model of successful aging.