Rest-activity rhythms and white matter microstructure across the lifespan.

Area of Science:

• Neuroscience
• Chronobiology
• Aging Research

Background:

• Rest-activity (RA) rhythm stability is crucial for overall health.
• White matter microstructure changes across the lifespan.
• The relationship between RA rhythm stability and brain structure is not fully understood, especially in healthy aging.

Purpose of the Study:

• To investigate the association between rest-activity rhythm stability and white matter microstructure in healthy young and older adults.
• To determine if this association differs across age groups.
• To explore the unique contribution of RA rhythm measures to white matter integrity.

Main Methods:

• Diffusion tensor imaging (DTI) and tract-based spatial statistics (TBSS) were used to analyze white matter microstructure.
• Actigraphy data over 7 days were used to calculate RA rhythm stability using cosinor and non-parametric methods.
• Region of interest analysis focused on the corpus callosum (CC).

Main Results:

• Greater rest-activity rhythm stability correlated with higher fractional anisotropy (FA), a marker of white matter integrity.
• This association was observed in both young and older adults, particularly in the corpus callosum and anterior corona radiata.
• RA rhythm stability uniquely explained variance in white matter integrity, independent of other sleep metrics.

Conclusions:

• The findings support a link between brain white matter structure and RA rhythm stability in healthy individuals.
• The relationship between RA rhythm stability and white matter integrity is consistent across adult age groups.
• Rest-activity rhythms may serve as a valuable biomarker for brain health throughout adulthood.