Dynamic Rest-to-Task Brain Network Reconfiguration Reveals Divergent Cognitive Changes in Aging

Abstract Emerging research challenges the prevailing notion of uniform cognitive decline in aging, instead emphasizing the brain's adaptive ability that compensates for age-related deficits. Here we examined age-related differences in brain dynamics by focusing on rest-to-task reconfiguration, a process that reflects the brain’s ability to recruit neural resources for goal-directed behavior. Using hidden Markov modeling of whole-brain fMRI data, we characterized brain state transitions from rest to a Stroop task in young and older adults. Behaviorally, older adults exhibited generalized slowing yet preserved conflict resolution. Dynamically, both age groups could reconfigure from rest-specific towards a task-efficient brain state. However, while young adults preferentially engaged this state, older adults showed attenuated recruitment, instead maintaining a high-effort state from rest to task. Crucially, the functional benefit of this pattern was conditional: it supported conflict resolution only in high-accuracy older adults but presented detrimental in low performers. These findings demonstrate that cognitive preservation in aging depends not on preserving youthful brain reconfiguration dynamics, but on the effective recruitment of compensatory brain states.