Abstract: Objective To investigate the mild cognitive impairment measured by necropsy ecological scales and the P300 of ERP in the patients with moderate-severe obstructive sleep apnea and hypopnea syndrome(OSAHS). Methods A total of 30 patients(patients group)who were monitored by Polysomnography(PSG)and 20 volunteers(controls groups)were enrolled, the 30 patients were carried out to determine whether the participants have mild Cognitive Impairment(MCI)by Montréal cognitive assessment scale(MoCA).Parallel Epworth sleepiness scale(ESS)and P300.All of them were monitored for apnea/hyponea index(AHI)、lowest oxygen saturation(LSaO₂)、mean oxygen saturation(MSaO₂)during sleep and the total sleep time of SaO₂<90%(CT90), the oxygen saturation index(ODI)、the respiratory micro arousal(RMI)and sleep structure. And compare the parameter one by one. Compare the various indicators and correlation the MoCA score, P300 parameters and the PSG parameters. Results Compared with the control group, the moderate-severe OSAHS patients, there was no significant statistically different in age and educational level. The BMI and ESS increased,the score of MoCA in OSAHS group strikingly lower than that of the control group, the MoCA analysis showed that memory/delayed recall score was significantly decreased, the AHI increased.the score of LSaO₂ and MSaO₂ decreased, CT90% increased, ODI and RMI increased significantly, the S1 and S2 prolonged, the S3、S4 and REM shortened, the Cz,C3,C4,Pz P300 latency was significantly prolonged in P300. Correlation analysis showed that the MoCA memory/delayed not associated with ESS, AHI, MSaO₂, CT90%, Cz, C3, C4, and was positively related to LSaO₂, and was negatively the RMI, ODI, CT90%, the latent period of Pz, the amplitude of Fz, Pz P300 latency and Fz P300 amplitude had significant influence on the MoCA. Conclusion Moderate-severe OSAHS patients existing MCI, the memory function of patients with OSAHS was significantly associated with the RMI which caused by the sleep structure disorder, P300 detection can be used as electric physiological indicator of cognitive dysfunction in OSAHS patients, combined the MoCA score can promptly evaluate the cognitive dysfunction in OSAHS patients, and promptly make a diagnosis and give treatment according to the evaluation result.

Key words: Sleep apnea, obstructive, Neuropsychological test, Cognitive function, Eventrelated potential P300, The Montreal cognitive assessment scale