Delineating cognitive resilience using fractal regulation: Cross‐sectional and longitudinal evidence from the Rush Memory and Aging Project

Abstract

AbstractINTRODUCTIONDegradation of fractal patterns in actigraphy independently predicts dementia risk. Such observations motivated the study to understand the role of fractal regulation in the context of neuropathologies.METHODSWe examined associations of fractal regulation with neuropathologies and longitudinal cognitive changes in 533 older participants who were followed annually with actigraphy and cognitive assessments until death with brain autopsy performed. Two measures for fractal patterns were extracted from actigraphy, namely, α1 (representing the fractal regulation at time scales of <90 min) and α2 (for time scales 2 to 10 h).RESULTSWe found that larger α1 was associated with lower burdens of Lewy body disease or cerebrovascular disease pathologies; both α1 and α2 were associated with cognitive decline. They explained an additional significant portion of the variance in the rate of cognitive decline above and beyond neuropathologies.DISCUSSIONFractal patterns may be used as a biomarker for cognitive resilience against dementia‐related neuropathologies.