Objective
Slow‐wave activity (SWA) during sleep is reduced in
people with amnestic mild cognitive impairment (aMCI) and is related to
sleep‐dependent memory consolidation. Acoustic stimulation of slow
oscillations has proven effective in enhancing SWA and memory in younger
and older adults. In this study we aimed to determine whether acoustic
stimulation during sleep boosts SWA and improves memory performance in
people with aMCI.
Methods
Nine adults with aMCI (72 ± 8.7 years) completed one
night of acoustic stimulation (stim) and one night of sham stimulation
(sham) in a blinded, randomized crossover study. Acoustic stimuli were
delivered phase‐locked to the upstate of the endogenous sleep
slow‐waves. Participants completed a declarative recall task with 44
word‐pairs before and after sleep.
Results
During intervals of acoustic stimulation, SWA increased by >10% over sham intervals (P < 0.01),
but memory recall increased in only five of the nine patients. The
increase in SWA with stimulation was associated with improved morning
word recall (r = 0.78, P = 0.012).
Interpretation
Acoustic stimulation delivered during slow‐wave sleep
over one night was effective for enhancing SWA in individuals with aMCI.
Given established relationships between SWA and memory, a larger or
more prolonged enhancement may be needed to consistently improve memory
in aMCI.
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