Cognitive Decline and Reorganization of Functional Connectivity in Healthy Aging: The Pivotal Role of the Salience Network in the Prediction of Age and Cognitive Performances

Abstract

Normal aging is related to a decline in specific cognitive processes, in particular in executive functions and memory. In recent years a growing number of studies have focused on changes in brain functional connectivity related to cognitive aging. A common finding is the decreased connectivity within multiple resting state networks, including the default mode network (DMN) and the salience network. In this study, we measured resting state activity using fMRI and explored whether cognitive decline is related to altered functional connectivity. To this end we used a machine learning approach to classify young and old participants from functional connectivity data. The originality of the approach consists in the prediction of the performance and age of the subjects based on functional connectivity by using a machine learning approach. Our findings showed that the connectivity profile between specific networks predicts both the age of the subjects and their cognitive abilities. In particular, we report that the connectivity profiles between the salience and visual networks, and the salience and the anterior part of the DMN, were the features that best predicted the age. Moreover, independently of the age of the subject, connectivity between the salience network and various specific networks (i.e., visual, frontal) predicted episodic memory skills either based on a standard assessment or on an autobiographical memory task, and short-term memory binding. Finally, the connectivity between the salience and the frontal networks predicted inhibition and updating performance, but this link was no longer significant after removing the effect of age. Our findings confirm the crucial role of episodic memory and executive functions in cognitive aging and suggest a pivotal role of the salience network in neural reorganization in aging.

Functional segregation loss over time is moderated by APOE genotype in healthy elderly

“…While as distinct functional networks, the ECN and the SN tended to share positive FC (He et al, ), consistent with their increased activation during cognitive tasks compared to the deactivated DMN. Past studies on healthy ageing have demonstrated the importance of the connectivity profile with the SN (Chand, Wu, Hajjar, & Qiu, ; Onoda, Ishihara, & Yamaguchi, ), for instance, by improving the classification success on episodic memory performance and executive function between young and old participants (La Corte et al, ). Lower ECN‐SN FC may suggest that APOE ‐ɛ4 carriers had aberrant communication between networks critical for externally oriented cognition compared to noncarriers.…”

Phases of Hyperconnectivity and Hypoconnectivity in the Default Mode and Salience Networks Track with Amyloid and Tau in Clinically Normal Individuals

“…Moreover, episodic memory is typically the most salient cognitive symptom of early AD and relies on the interplay of DMN and MTL activity (Miller et al, 2008;. Executive function also commonly declines in concert with episodic memory in aging and early AD, which may particularly implicate interplay between DMN network and salience networks (La Corte et al, 2016). Ongoing work in our group and others seeks to further differentiate the network alterations associated with aging and the earliest alterations specifically associated with the molecular pathologies of AD.…”

Impact of sex and reproductive status on memory circuitry structure and function in early midlife using structural covariance analysis

“…Approximately 75% of the aging population report memory‐related problems (Koivisto et al, ). The decline in cognitive ability is not limited to neurodegenerative diseases, but also part of healthy aging (La Corte et al, ; van Geldorp et al, ) and has substantial consequences for quality of life (Hannigan, Coen, Lawlor, Robertson, & Brennan, ) and mortality (Connors et al, ). While most aging studies target individuals 65 years and older (e.g., Boutet, Milgram, & Freedman, ; Caselli, Chen, Lee, Alexander, & Reiman, ; Metzler‐Baddeley, Jones, Belaroussi, Aggleton, & O'Sullivan, ), recent research showed that brain structural and functional abnormalities can precede classical age‐related neurodegeneration decades earlier (Szoeke et al, ).…”

“…Approximately 75% of the aging population report memory-related problems (Koivisto et al, 1995). The decline in cognitive ability is not limited to neurodegenerative diseases, but also part of healthy aging (La Corte et al, 2016;van Geldorp et al, 2015) and has substantial consequences for quality of life (Hannigan, Coen, Lawlor, Robertson, & Brennan, 2015) and mortality (Connors et al, 2015).…”