Functional reconfiguration between rest and movie watching relates to theory-of-mind performance among young and older adults.

Functional connectivity among macroscale brain networks is minimally modified across rest and task states, suggesting a shared functional architecture supporting efficient neural processing. The extent of reconfiguration (ie change between states), moreover, shows individual variation, with less reconfiguration generally being associated with better task performance. Older adults reconfigure more than young adults when completing goal-directed tasks with known age deficits. Less is known about task states that more closely mirror the complexity of daily life. Thus, we examined reconfiguration between rest and passive viewing of a mockumentary television show, involving richly contextualized social interactions, among young (18 to 35 years; N = 101) and older (61 to 92 years; N = 83) adults. Then, we related reconfiguration to participants' accurate understanding of those social interactions (theory of mind) on a novel task conducted outside of the scanner. Consistent with prior work, older adults exhibited greater cortical reconfiguration and worse theory-of-mind performance compared to young adults. Greater reconfiguration related to worse theory-of-mind performance, and the default and frontoparietal networks most strongly contributed to this association. These findings provide greater insight into how reduced neural specializations with age disrupt social cognition even in the absence of an explicit task.