Associations Between Excessive Daytime Sleepiness, Cognitive Impairment, and Brain Alterations in Patients With Obstructive Sleep Apnea

BACKGROUND: Excessive daytime sleepiness (EDS) substantially impairs health-related quality of life and cognitive function in obstructive sleep apnea (OSA) patients. However, the underlying neuropathological mechanisms remain poorly understood. PURPOSE: To investigate the associations between EDS, cognitive deficits, and brain alterations in OSA patients. STUDY TYPE: Prospective. POPULATION: One hundred two OSA patients (16 female, median age (IQR) 33.00 [28.00-41.00]) and 86 healthy controls (HCs) (16 female, median age (IQR) 33.00 [25.00-50.25]) were prospectively recruited. FIELD STRENGTH/SEQUENCE: 3 T, 3D spoiled gradient-echo, diffusion-weighted spin-echo, blood oxygen level-dependent gradient-echo planar. ASSESSMENT: The Epworth Sleepiness Scale, multiparameter MRI, and a series of neuropsychological tests (the number connection tests A and B, digit symbol test, line tracing test, serial dotting test, and Stroop Color/Word test) were performed to evaluate EDS, brain alterations, and cognitive performances. STATISTICAL TESTS: Mann-Whitney U test, independent samples t-test, chi-square test, Spearman's correlation, and mediation analyses were used. Significance level: p < 0.05. RESULT: OSA patients exhibited statistically poorer cognitive performance (effect size = 0.23-0.37), lower diffusion tensor imaging along the perivascular space (DTI-ALPS) index (effect size = 0.25), and abnormal network topology (effect size = -0.80 to 0.57) compared with HCs. EDS significantly correlated with poorer cognitive performance (r = -0.173 to 0.258), lower DTI-ALPS index (r = -0.199), and abnormal network topology (r = -0.364 to 0.279) in all participants. Furthermore, aberrant degree centrality and nodal efficiency in the bilateral middle frontal gyrus (MFG) and left inferior parietal lobule (IPL) may mediate the relationship between EDS and cognitive deficits (indirect effect = -0.13 to 0.36). DATA CONCLUSION: These results demonstrate that cognition, DTI-ALPS index, and network topology were all compromised in OSA. Furthermore, abnormal network topology in the bilateral MFG and left IPL may mediate the relationship between EDS and cognitive deficits. EVIDENCE LEVEL: Level 2. TECHNICAL EFFICACY: Stage 2.