Relationship of apnea-hypopnea index, NREM stage 3 duration, and arousal index with cognitive functions: A PSG-based assessment in individuals with obstructive sleep apnea syndrome

Relationship of Apnea-Hypopnea Index, NREM Stage 3 Duration, and Arousal Index with Cognitive Functions: A PSG-Based Assessment in Individuals with Obstructive Sleep Apnea Syndrome Objective: The aim of this study is to retrospectively investigate the relationship between polysomnography (PSG) parameters—such as apnea hypopnea index (AHI), NREM stage 3 duration, REM duration, arousal index, and ST90 duration—and Mini-Mental State Examination (MMSE) scores in individuals diagnosed with obstructive sleep apnea syndrome (OSAS). Our study aims to reveal that OSAS affects not only respiratory but also cognitive functions, emphasizing the necessity of regular neurocognitive evaluation in these patients. Materials and Methods: This retrospective cross-sectional study included 90 patients diagnosed with OSAS based on PSG findings. The demographic characteristics and PSG data of the patients were recorded, and all participants underwent the Mini-Mental State Examination. Correlation analyses were performed to evaluate the relationships between sleep parameters and cognitive performance. Results: According to the study findings, a significant negative correlation was found between AHI and MMSE (r=-0.256; p=0.015). The arousal index also showed a negative correlation with MMSE scores (r=-0.219; p=0.038). A significant negative correlation was detected between ST90 and MMSE scores (r=- 0.300; p=0.004). NREM stage 3 duration (p=0.587), REM duration (p=0.237), and sleep efficiency percentage (p=0.129) were positively but not significantly correlated with cognitive performance. Conclusion: In individuals with OSAS, decreased cognitive function is associated with sociodemographic factors such as age and education level, as well as OSAS severity, duration of exposure to OSAS, hypoxic burden, and sleep fragmentation. Although reductions in sleep efficiency percentage, NREM stage 3 duration, and REM duration were not statistically significant, they tended to negatively affect overall cognitive performance. These findings indicate that OSAS should be considered not only as a respiratory disorder but also in terms of its neurocognitive consequences. Early diagnosis and a multidisciplinary approach are important for improving quality of life and preventing potential dementia development. Keywords: Obstructive Sleep Apnea Syndrome, Cognitive Function, Mini-Mental State Examination, Polysomnography