The association between obstructive sleep apnea and neurocognitive performance--the Apnea Positive Pressure Long-term Efficacy Study (APPLES).

Study Objectives: To determine associations between obstructive sleep apnea (OSA) and neurocognitive performance in a large cohort of adults.
Study Design: Cross-sectional analyses of polysomnographic and neurocognitive data from 1204 adult participants with a clinical diagnosis of obstructive sleep apnea (OSA) in the Apnea Positive Pressure Long-term Efficacy Study (APPLES), assessed at baseline before randomization to either continuous positive airway pressure (CPAP) or sham CPAP.
Measurements: Sleep and respiratory indices obtained by laboratory polysomnography and several measures of neurocognitive performance.
Results: Weak correlations were found for both the apnea hypopnea index (AHI) and several indices of oxygen desaturation and neurocognitive performance in unadjusted analyses. After adjustment for level of education, ethnicity, and gender, there was no association between the AHI and neurocognitive performance. However, severity of oxygen desaturation was weakly associated with worse neurocognitive performance on some measures of intelligence, attention, and processing speed.
Conclusions: The impact of OSA on neurocognitive performance is small for many individuals with this condition and is most related to the severity of hypoxemia.