Continuous Positive Airway Pressure Effect on the Changes of Regional Brain Activity in Patients with Severe Obstructive Sleep Apnea-Hypopnea Syndrome

Objective: This study aimed to evaluate the effect of continuous positive airway pressure (CPAP) effect on the cognitive function in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS).Methods: Twenty-four severe OSAHS patients diagnosed by polysomnography (PSG), and twenty-two healthy adults were included. OSAHS group underwent Epworth Sleepiness Scale (ESS), Montreal Cognitive Assessment (MoCA) score, and restingstate functional magnetic resonance imaging (rs-fMRI) scan before and after CPAP therapy. A statistical map of different brain regions of regional homogeneity (ReHo) was obtained by rs-fMRI images process with Matlab. Cognitive function brain areas in patients with OSAHS were assessed by evaluating changes of cognitive function and neurological function imaging to evaluate the clinical efficacy of CPAP.Results: Compared with the healthy control group, the apnea-hypopnea index (AHI), oxygen desaturation index (ODI) and ESS score were significantly increased, while the lowest oxygen saturation (LSaO2), mean oxygen saturation (MSaO2) and MoCA score were significantly decreased (p < 0.05) before treatment in OSAHS group. In OSAHS group, AHI, ODI and ESS scores after CPAP treatment were significantly lower than before treatment, while LSaO2, MSaO2 and MoCA scores were significantly higher than before treatment (p < 0.05). ESS scores in OSAHS group were significantly positively correlated with AHI (r = 0.687, p < 0.05) and ODI (r = 0.541, p < 0.05), and MoCA scores were significantly negatively correlated with AHI (r = -0.801, p < 0.05) and ODI (r = -0.783, p < 0.05). The ReHo values of the right angular gyrus, right precuneus, left parahippocampal gyrus, and left middle frontal gyrus were reduced in the OSAHS group at baseline compared to the healthy control group, while the ReHo values in the right posterior lobe of the cerebellum increased. The ReHo value of the right posterior cerebellar lobe in the OSAHS group and the healthy control group was positively related to the MoCA score (r = 0.324,p < 0.05). The ReHo value of the right precuneus before and after CPAP treatment in the OSAHS group was positively related to AHI (r = 0.478, p < 0.05) and negatively correlated to the MoCA score (r = 0.484,p < 0.05).Conclusions: Patients with severe OSAHS generally have cognitive dysfunction, and the structure and function of several brain regions have abnormal changes. After CPAP intervention for 3 months in patients with severe OSAHS, the neural activities of the left limbic lobe, right temporal lobe, posterior cingulate gyrus, and precuneus were increased. Changes in brain activity in these regions may be the neural functional basis for the emergence of cognitive function.