Electrophysiological and neuropsychological outcomes of severe obstructive sleep apnea: effects of hypoxemia on cognitive performance
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Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized with upper airway obstructions. Some studies showed cognitive and electrophysiological changes in patients with OSAS; however, contradictory results were also reported. The purpose of the present study was twofold: (1) to investigate cognitive changes in severe OSAS patients by using neuropsychological tests and electrophysiological methods together, (2) to investigate influence of hypoxemia levels on cognition. Fifty-four severe OSAS patients and 34 age-, gender- and education matched healthy subjects were participated. OSAS patients were further divided into two subgroups according to minimum oxygen saturation levels. All participants underwent a detailed neuropsychological test battery. A classical visual oddball task was used to elicit ERP P300 and mean P300 amplitudes were measured from Fz, Cz and Pz electrode sites. OSAS patients showed reduced mean P300 amplitudes up to 43–51% on all electrode sites compared to healthy controls. Subgroup analysis revealed significant differences in neuropsychological test scores between healthy controls and high hypoxemia OSAS group, as well as between low and high hypoxemia groups. Moreover, both low and high hypoxemia OSAS groups had lower P300 amplitudes compared with healthy controls. P300 amplitudes showed a gradual decline in parallel with increasing hypoxemia severity; however, the difference between high and low hypoxemia OSAS groups did not reach significance. Moderate correlations were found between sleep parameters, neuropsychological test scores and P300 amplitudes. These results suggest that electrophysiological measures could be better indicators of cognitive changes than neuropsychological tests in OSAS, particularly in mildly affected patients.
KeywordsObstructive sleep apnea syndrome OSAS Event-related potentials P300 Neuropsychological tests Hypoxemia
This study was supported by Dokuz Eylul University Scientific Research Projects (Project Number: 2014.KB.SAG.058).
- American Academy of Sleep Medicine (2005) Diagnostic and coding manual, 2nd edn. American Academy of Sleep Medicine; International classification of sleep disorders, WestchesterGoogle Scholar
- Heaton RK, Chelune GJ, Talley JL, Kay GG, Curtiss G (1993) Wisconsin card sorting test manual: revised and expanded. Psychological Assessment Resources, FloridaGoogle Scholar
- Iber C, Ancoli-Israel S, Chesson A, Quan SF (2007) Westchester, IL: American Academy of Sleep Medicine; 2007. The AASM manual for the scoring of sleep and associated events: rules, terminology and technical specifications, pp 48–49Google Scholar
- Kaplan E, Goodglass H, Weintraub S (2001) Boston naming test. Pro-ed, AustinGoogle Scholar
- Öktem Ö (1992) A verbal test of memory processes. Arch Neuropsychiatry 29:196–206Google Scholar
- Strauss E, Sherman EM, Spreen O (2006) A compendium of neuropsychological tests: administration, norms, and commentary. Oxford University Press, OxfordGoogle Scholar
- Wechsler D (1987) Wechsler memory scale-revised (WMS-R). Psychological Corporation, San AntonioGoogle Scholar
- Wechsler D (2008) Wechsler adult intelligence scale–Fourth Edition (WAIS–IV). San Antonio, TX: NCS Pearson 22, 498Google Scholar