Brain network changes and memory decline in aging

Abstract

One theory of age-related cognitive decline proposes that changes within the default mode network (DMN) of the brain impact the ability to successfully perform cognitive operations. To investigate this theory, we examined functional covariance within brain networks using regional cerebral blood flow data, measured by 15O-water PET, from 99 participants (mean baseline age 68.6 ±7.5) in the Baltimore Longitudinal Study of Aging collected over a 7.4 year period. The sample was divided in tertiles based on longitudinal performance on a verbal recognition memory task administered during scanning, and functional covariance was compared between the upper (improvers) and lower (decliners) tertile groups. The DMN and verbal memory networks (VMN) were then examined during the verbal memory scan condition. For each network, group differences in node-to-network coherence and individual node-to-node covariance relationships were assessed at baseline and in change over time. Compared with improvers, decliners showed differences in node-to-network coherence and in node-to-node relationships in the DMN but not the VMN during verbal memory. These DMN differences reflected greater covariance with better task performance at baseline and both increasing and declining covariance with declining task performance over time for decliners. When examined during the resting state alone, the direction of change in DMN covariance was similar to that seen during task performance, but node-to-node relationships differed from those observed during the task condition. These results suggest that disengagement of DMN components during task performance is not essential for successful cognitive performance as previously proposed. Instead, a proper balance in network processes may be needed to support optimal task performance.

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

“…Lower ECN‐SN FC may suggest that APOE ‐ɛ4 carriers had aberrant communication between networks critical for externally oriented cognition compared to noncarriers. While we did not observe a reliable linear relationship between the cross‐sectional changes in the ECN‐SN FC and visuospatial memory performance, both networks subserve functions related to cognitive control processes that are important for carrying out cognitive tasks (Beason‐Held, Hohman, Venkatraman, An, & Resnick, ; Suri et al, ). Therefore, one possible hypothesis is that carriers have altered regulation of control processes that subsequently influence their memory performance.…”

“…4.2 | APOE-E4 was associated with lesser coupling between task-positive intrinsic connectivity networks but not within-networks across individuals Resnick, 2017;Suri et al, 2017). Therefore, one possible hypothesis is that carriers have altered regulation of control processes that subsequently influence their memory performance.…”

Disrupted Interhemispheric Synchrony in Default Mode Network Underlying the Impairment of Cognitive Flexibility in Late-Onset Depression

“…in MDD. Meanwhile, recent studies and our previous results suggested that the changed network processes in DMN were related to the impairment of cognitive performance, and the balance in DMN, CCN and salience network processes are essential to maintain optimal cognitive function (Wu et al, 2013 ; Beason-Held et al, 2016 ). It is feasible to study the potential correlation between VMHC in DMN and cognitive dysfunction, for it provides a new perspective for understanding the role of DMN in the process of cognitive decline in LOD.…”

Shall We Dance? Dancing Modulates Executive Functions and Spatial Memory

“…Aging is considered in some studies as one of the most prominent problems in the short and medium term for modern societies [1], demanding more support and investment in health systems. It is widely accepted that normal aging is associated with a decline in brain functions [2], disturbing, among others, executive and memory processes [3].…”