Sleep structure and cognitive function in stoke combined with obstructive sleep apnea hypopnea syndrome

Abstract

Objective To explore characteristics of sleep structure and the correlation with cognitive function in cerebral infarction combined with obstructive sleep apnea hypopnea syndrome (CI-OSAHS). Methods The patients with CI-OSAHS and OSAHS in Department of Neurology and Breathing Sleep Monitoring Room of Tianjin Medical University General Hospital from December 2009 till March 2011 were collected. All the patients completed polysomography（PSG）. Sixty patients were selected and divided into 3 groups based on PSG. These 3 groups were combined group 20 persons (CI-OSAHS), OSAHS group 20 persons (OSAHS) and control group 20 persons (without cerebral infarction obstructive sleep apnea hypopnea syndrome). All the patients completed image examinations (CT and MRI) evaluation of the cognitive function by Mini-Mental State Examination（MMSE）and Montreal Cognitive Assessment（MoCA）. Results Sleep structure: the awake time, non-rapid eye movement sleep （NREM ）1, NREM 2 and NREM periods in combined group and OSAHS group were significantly longer, the NREM3+4 and rapid eye movement（REM） periods were shorter than the control group. The NREM and NREM 1 periods in combined group were longer, the NREM 3+4 and REM periods were shorter than the OSAHS group. The correlation analysis of cognitive function and breathing disorders and low oxygen related index: there was negative correlation between the total scores of cognitive function（MMSE and MoCA）and apnea hyponea index, oxygen desaturation index (ODI) (MMSE r=-0.450, -0.671, MoCA r=-0.486, -0.494, all P<0.05) while, was positive correlation between them and noctumal average hypoxemia and minimum hypoxemia (MMSE r=0.477, 0.485, MoCA r=0.507, 0.482, all P<0.05) in the OSAHS group. There was negative correlation between ODI, arousal index and the total scores of MoCA in the combined group (MoCA r=-0.463, 0.480, both P<0.05), there was correlation between the total scores of MMSE and the other sleep parameters, but，there was no difference in statistics. The correlation analysis of cognitive function and sleep stages: There was positive correlation between the total scores of cognitive function（MMSE and MoCA）and the NREM 3+4 periods （r=0.521，0.474，both P<0.05）while, there was negative correlation between the total scores of MMSE and the NREM 1+2 periods（r=-0.458, P<0.05） in the OSAHS group. There was positive correlation between the REM period and the total scores of MoCA （r=0.472，P<0.05）. There was correlation between the total scores of MMSE and the sleep structure, but,there was no difference in statistics in combined group. Conclusions Patients with OSAHS have obvious sleep structure disorder. The awake time and light sleep periods are significantly longer than the control group, while, the deep sleep and REM periods are significantly shorter than the control group. The NREM 1 of the patients with CI-OSAHS is longer than the patients with OSAHS. The higher the AHI, the lower the night blood oxygen, the more obvious cognitive dysfunction. The longer the awake time, the longer the light sleep, the shorter the deep sleep and REM periods, the more serious cognitive dysfunction.The correlation between the cognitive impairment and low oxygen is more apparent than sleep structure. There is apparent correlation among the total scores of MoCA, the degree of hypoxia and sleep structure in the patients with CI-OSAHS. The total scores of MoCA are more sensitivity than MMSE in mild vascular cognitive impairment. Key words: Sleep apnea; obstructive; Brain infarction; Cognition disorders; Sleep disorders; Polysomnography