Hierarchical disruption of lateral prefrontal cortex gradients in cognitive aging.

The lateral prefrontal cortex (LPFC) plays a pivotal role in executive functions and exhibits a hierarchical rostro-caudal organization critical for higher-order cognition. Using connectome gradient mapping of resting-state fMRI data across young, middle-aged, and older adults (N = 478), we found preserved global gradient structure but significant compression of the principal gradient in older adults relative to middle-aged adults, particularly in dorsolateral (DLPFC) and frontopolar (FPC) regions. This reduced functional differentiation corresponded to lower spatial separation between LPFC subdivisions. Meta-analytic decoding linked these changes to attenuated engagement of executive functions. Crucially, in an independent cohort of older adults (N = 99), individuals with better executive function exhibited greater gradient range and variation at the global level, along with higher gradient values in the DLPFC and ventrolateral prefrontal cortex (VLPFC) and lower values in the premotor cortex at the regional level. These findings suggest that age-related disruption of LPFC gradient organization may reflect neural dedifferentiation and is closely related to executive decline. Gradient compression in the LPFC may serve as a novel biomarker of cognitive aging, offering insights into the hierarchical reorganization of brain networks in late life.