Detection of mild cognitive impairment in middle-aged and older adults with obstructive sleep apnoea: does excessive daytime sleepiness play a role?

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How sleepiness can inform clinicians about the presence of cognitive deficits and the risk of further cognitive decline in older adults is an intriguing question. The comments made by P. Steiropoulos and co-workers in their correspondence led us to perform supplementary analyses using the Epworth Sleepiness Scale in our cohort [1]. We first explored whether the presence of self-reported sleepiness modified the prevalence of mild cognitive impairment (MCI) in subjects with obstructive sleep apnoea (OSA) (mild, moderate and severe OSA were combined) and controls. In the OSA group, MCI tended to be less prevalent in subjects reporting sleepiness (Epworth Sleepiness Scale score of 10 and higher) compared to those reporting no sleepiness. More specifically, MCI was found in 31.7% of sleepy subjects and in 45.6% of nonsleepy OSA participants (χ²(1)=2.05; p=0.15). In the control group, sleepiness was not associated with a higher prevalence of MCI (37.5% had MCI in nonsleepy controls compared to 33.3% with MCI in sleepy control subjects; χ²(1)=0.03; p=0.86). When the association between sleepiness and MCI subtypes was explored (i.e. amnestic versus non-amnestic and single cognitive domain affected versus multiple cognitive domains affected), no group differences were found between OSA subjects with and without sleepiness (figure 1). Our exploratory results suggest that self-reported daytime sleepiness is not associated with increased neurocognitive impairments in our cohort of OSA and control participants.