Researchers analyzed resting-state brain connectivity in nearly 1,100 adults across two cohorts and discovered that normal aging and Alzheimer's disease (AD) each reorganize brain communication along separate fundamental axes. Aging consistently reshuffled connectivity along the 'representational–executive' axis, with executive regions gaining and representational regions losing connectivity throughout adult life. AD pathology instead disrupted the 'sensory–association' axis, reducing connectivity in sensorimotor areas while increasing it in associative regions. These changes were detectable even before cognitive symptoms appeared, and gradient-aligned connectivity shifts correlated with domain-specific cognitive performance. The findings provide a unifying framework for interpreting contradictory prior connectivity literature and suggest these distinct neural signatures could become early biomarkers of AD vulnerability.
