The Effects of Sleep Apnea and Variables on Cognitive Function and the Mediating Effect of Depression

Park, Kyung Won; Kim, Hyeong Wook; Choi, Mal Rye; Kim, Byung Jo; Kim, Tae Hyung; Song, Ok Sun; Eun, Hun Jeong

Abstract

OBJECTIVES
This study aimed to analyze causality among sleep apnea, depression and cognitive function in patients with obstructive sleep apnea.
METHODS
We reviewed the medical records of 105 patients with sleep apnea and snoring who underwent overnight polysomnography (PSG). We analyzed various biological data, sleep variables (sleep duration and percentage) and respiratory variables [arousal index (AI), periodic leg movement index (PLM index), snoring Index (SI), mean SpO2, minimum SpO2, apnea-hypopnea index (AHI), and respiratory disturbance index (RDI)]. We also analyzed various data by sleep, cognition, and mood related scales: Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale (ESS), snoring index by scale (SIS), Montreal Cognitive Assessment-Korean (Moca-K), Mini-mental State Examination-Korean (MMSE-K), clinical dementia rating (CDR), and Beck Depression Inventory (BDI). We analyzed causation among sleep, and respiratory, mood, and cognition related scales in obstructive sleep apnea patients. We analyzed the mediating effects of depression on sleep apnea patient cognition.
RESULTS
As Duration N1 increased and Total sleep time (TST) decreased, MOCA-K showed negative causality (p < 0.01). As BDI and supine RDI increased, causality was negatively related to MOCA-K (p < 0.01). As PSQI (p < 0.001) and SIS (p < 0.01) increased and as MMSE-K (p < 0.01) decreased, causality was positively related to BDI. BDI was found to mediate the effect of age on MOCA-K in patients with obstructive sleep apnea.
CONCLUSION
Duration N1, total sleep time, BDI, and supine RDI were associated with cognitive function in obstructive sleep apnea patients. Depression measured by BDI partially mediated cognitive decline in obstructive sleep apnea patients.