Age-related cortical signatures of human sleep electroencephalography.

Accumulating evidence demonstrates a direct relationship between impaired neural integrity and disrupted sleep physiology in normal and pathological aging. However, previous work has focus almost exclusively on nonrapid eye movement sleep electroencephalography as a proxy of cortical integrity with aging. Whether this relationship holds true for rapid eye movement sleep electroencephalography is unknown. Our results show that age-related reduction in low-frequency delta activity during both rapid eye movement and nonrapid eye movement sleep was statistically mediated by the thinning of the medial frontal and anterior cingulate cortices. These findings (1) support the potential role of the medial frontal and cingulate cortices, major hubs of the human brain, in synchronizing neuronal assemblies during sleep, and (2) suggest that, with age, a reduction in cortical integrity within this frontal network mediates the loss of delta power during sleep. Further work will determine whether cortical thinning and delta loss may interact and contribute to cognitive decline with aging.