Are cognitive deficits observed in obstructive sleep apnea associated with cognitive complaints?

Abstract

Introduction Obstructive sleep apnea (OSA) causes sleep disruption and intermittent nocturnal hypoxemia, which can lead to daytime sleepiness and cognitive deficits. Cognitive deficits reported by individuals suffering from OSA can be severe enough to warrant a diagnosis of mild cognitive impairment (MCI). However, no study has focused on the specific cognitive complaints reported by OSA patients. Objectives: To investigate the cognitive complaints reported by OSA patients compared to control subjects, and to explore whether the presence of MCI in OSA is associated with increased or different cognitive complaints. Materials and methods Thirty-four subjects with OSA (apnea–hypopnea index (AHI) mean: 32.5 ± 14.5; mean age: 63.4 ± 6.5 yrs) and 24 healthy controls (mean age: 64.3 ± 6.5 yrs), matched for sex and education, underwent an overnight polysomnography and a comprehensive neuropsychological assessment. All participants filled out the following questionnaires: Cognitive failure questionnaire (CFQ), a French adapted version of Cognitive Difficulties Scale (CDS), Beck depression inventory-II (BDI-II), Beck anxiety inventory (BAI) and Epworth Sleepiness Scale (ESS). MCI was defined as an objective evidence of cognitive decline and no major impact of cognitive deficits on activities of daily living. Groups were compared on respiratory variables, demographic characteristics and questionnaires using Student t -tests. Results Although OSA and control groups differ on body mass index ( t (48) = 2.29, p t (48) = 18.83, p n = 14) and non-MCI ( n = 20) sub-groups, no significant groups differences was observed for frequency or type of cognitive complaints: CFQ (OSA N-MCI: 30.9 ± 2.9, OSA MCI: 28.4 ± 1.8), CDS (OSA N-MIC: 35.3 ± 15.7, OSA MCI: 33.4 ± 15.7). No other group difference was found, except for a lower education in OSA patients with MCI compared with OSA without MCI and control subjects. Conclusion Patients with OSA do not have more or different self-reported cognitive impairments than healthy subjects. This absence of group difference was also found for OSA patients with a diagnosis of MCI. Further studies should investigate whether OSA patients with MCI are aware of their cognitive impairments and if the questionnaires used in this study are sensitive enough to detect self-reported cognitive difficulties among this population. Acknowledgements Supported by the Canadian Institutes of Health Research and the Fonds de recherche du Quebec – Sante