Objectives: Obstructive sleep apnea (OSA) is associated with cognitive impairment but the relationships between specific biomarkers and neurocognitive domains remain unclear. The present study examined the influence of common health comorbidities on these relationships. Adults with suspected OSA (N=60; 53% male; M age=52 years; SD=14) underwent neuropsychological evaluation before baseline polysomnography (PSG). Apneic syndrome severity, hypoxic strain, and sleep architecture disturbance were assessed through PSG.
Methods: Depression (Center for Epidemiological Studies Depression Scale, CESD), pain, and medical comorbidity (Charlson Comorbidity Index) were measured via questionnaires. Processing speed, attention, vigilance, memory, executive functioning, and motor dexterity were evaluated with cognitive testing. A winnowing approach identified 9 potential moderation models comprised of a correlated PSG variable, comorbid health factor, and cognitive performance.
Results: Regression analyses identified one significant moderation model: average blood oxygen saturation (AVO2) and depression predicting recall memory, accounting for 31% of the performance variance, p<.001. Depression was a significant predictor of recall memory, p<.001, but AVO2 was not a significant predictor. The interaction between depression and AVO2 was significant, accounting for an additional 10% of the variance, p<.001. The relationship between low AVO2 and low recall memory performance emerged when depression severity ratings approached a previously established clinical cutoff score (CESD=16).
Conclusions: This study examined sleep biomarkers with specific neurocognitive functions among individuals with suspected OSA. Findings revealed that depression burden uniquely influence this pathophysiological relationship, which may aid clinical management. (JINS, 2018, 28, 864-875).
Keywords: Adults; Cognition; Depression; Human; Memory; Polysomnography.