Sleep slow waves’ negative-to-positive-phase transition : a marker of cognitive and apneic status in aging
Article [Accepted Manuscript]
Abstract(s)
The sleep slow-wave (SW) transition between negative and positive phases is thought to mirror synaptic strength and likely depends
on brain health. This transition shows signifcant age-related changes but has not been investigated in pathological aging. The present
study aimed at comparing the transition speed and other characteristics of SW between older adults with amnestic mild cognitive
impairment (aMCI) and cognitively normal (CN) controls with and without obstructive sleep apnea (OSA). We also examined the association of SW characteristics with the longitudinal changes of episodic memory and executive functions and the degree of subjective
cognitive complaints. aMCI (no/mild OSA = 17; OSA = 15) and CN (no/mild OSA = 20; OSA = 17) participants underwent a night of polysomnography and a neuropsychological evaluation at baseline and 18 months later. Participants with aMCI had a signifcantly slower
SW negative-to-positive-phase transition speed and a higher proportion of SW that are “slow-switchers” than CN participants. These
SW measures in the frontal region were signifcantly correlated with memory decline and cognitive complaints in aMCI and cognitive
improvements in CN participants. The transition speed of the SW that are “fast-switchers” was signifcantly slower in OSA compared to
no or mild obstructive sleep apnea participants. The SW transition-related metrics showed opposite correlations with the longitudinal
episodic memory changes depending on the participants’ cognitive status. These relationships were particularly strong in participants
with aMCI. As the changes of the SW transition-related metrics in pathological aging might refect synaptic alterations, future studies
should investigate whether these new metrics covary with biomarker levels of synaptic integrity in this population.
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