Age-Related Changes in Spontaneous Brain Dynamics Revealed by Resting-State Magnetoencephalography.

Spontaneous neuronal oscillations support large-scale brain communication and are sensitive to adult aging, yet how their moment-to-moment dynamics change across the adult lifespan and relate to cognition remains unclear. Here, we used resting-state magnetoencephalography (MEG) and time-delay embedded hidden Markov modelling to characterize transient oscillatory brain states in 617 healthy adults aged 18-88 years. Aging was associated with a frequency- and region-specific reorganization of spontaneous activity, characterized by increased anterior delta/theta power and reduced posterior alpha and sensorimotor beta power. At the network level, older adults showed lower fractional occupancy of a posterior state dominated by alpha activity. Within this posterior state, stronger alpha-band connectivity was modestly associated with better Addenbrooke's Cognitive Examination-Revised (ACE-R) performance, suggesting that posterior alpha coupling is related to individual differences in global cognitive performance as captured by this measure. Together, these findings reveal subtle age-related differences in spontaneous brain dynamics across the adult lifespan, including a posterior-to-anterior redistribution of state occupancy. Rather than establishing a clinical biomarker or a general marker of cognitive aging, the present results identify posterior alpha connectivity as a behaviorally relevant resting-state MEG feature that warrants further validation in longitudinal and multimodal studies.