Memory-related default-executive coupling across the lifespan and associations with changes in cognitive control

Episodic memory and cognitive control decline in aging. The default-executive coupling hypothesis of aging (DECHA) suggests that a neural correlate of cognitive decline in aging is increased functional connectivity (FC) between lateral prefrontal areas and the default-mode network. Here, in a lifespan sample (n = 552, 6-81 years), we tested FC between the left dorsolateral prefrontal cortex (dLPFC) and the default-mode network (DMN) during the encoding and retrieval phases of an episodic memory fMRI task. We created two age groups based on evidence for episodic memory decline after 30 years: a younger group encompassing childhood, adolescence, and young adulthood (6-29 years) and an aging group (30-81 years). To test whether the dLPFC-DMN FC was associated with changes in cognitive control, we used longitudinal change (up to 10 years) in a Stroop inhibition/switching task linked to the prefrontal cortex. Results showed (i) lower dLPFC and DMN connectivity with age in the younger group and higher connectivity in the aging group, and (ii) this FC was associated with an age-related increase in the inhibition task completion time, particularly in the aging group. However, dLPFC showed similar relationships with other networks, particularly salient attentional and control subnetworks, and despite decline in cognitive control associated with memory performance, memory-related FC between dLPFC and DMN did not.