Objective:

In this study, we propose to study brain networks functional connectivity at rest as well as the networks’ task-evoked BOLD response during two different tasks that have previously shown both age-related decline and improvement in performance

Background:

Brain aging - with and without pre-clinical Alzheimer’s disease (AD) pathology - are associated with deterioration in the brain networks’ coherence and/or co-activation/deactivation as well as with decline in most cognitive abilities, paving the road for a network-based conceptualization of the brain normal versus pathological aging. However, certain cognitive abilities, like crystallized memory, improve with age, which complicates the explanation of these changes solely through age-related decline in the brain networks.

Design/Methods:

Cross-sectional cohort of 259 participants (62 young, and 197 older), who underwent two task-based (one declining and another improving with age), and one resting-state fMRI scans, plus a positron emission tomography scan (to determine preclinical amyloid accumulation)

Results:

We found that the brain networks’ co-activation/deactivation, but not coherence, significantly attenuate with age and/or AD pathology even in the task for which performance improves by age. Interestingly, we also found that an increase in the networks’ co-activation/deactivation, but not coherence, was associated with an improvement in task performance. Finally, we provided preliminary evidence that the brain networks lose their task-evoked deactivations with age before their coherence.

Conclusions:

These findings shed light on the process of functional aging in the brain networks, differentiate functional aging of the brain networks’ coherence at rest versus their task-evoked co-activation/deactivation, and emphasize the more dominant role of the task-evoked brain activity in understanding aging brain function and distinguishing it from preclinical AD.