Correlation Between Cognitive Function And The MRI Of Brain Structure Changes In Patients With Obstructive Sleep Apnea Hypopnea Syndrome

Objectives To analyze the relationship between the cognitive impairment and thechanges of hippocampal structure and cerebral white matter in brain magnetic resonanceimaging (MRI) of subjects with obstructive sleep apnea hypopnea (OSAHS).Methods Eighty one snoring patients were monitored by overnightpolysomnography (PSG) in sleep center of the Second Affiliated Hospital of SoochowUniversity from March2012to August2013. Based on the results of apnea-hypopneaindex(AHI),they were divided into four groups: mild OSAHS group (n=23), moderateOSAHS group (n=18), severe OSAHS group (n=23) and primary snoring group (n=17).Periventricular hyperintensity (PVH) related to the severity of cerebral white matter lesionsand hippocampal atrophy were evaluated according to the Fukudas method and Scheltensstandard in brain MRI, used regular sequence and perpendicular to the bilateralhippocampal fluid attenuated inversion recovery (FIAIR) sequence. Montreal CognitiveAssessment (MoCA) and Mini-Mental State Examination (MMSE) were performed toevaluate the changes of cognitive function in all subjects. We analyzed the change and therelationship between brain structure and metabolism of lipid, coagulation function andhematokrit in patients with OSAHS.Results The cognitive function scores, especially the MoCA scores progressivelydecreased, and the scores of hippocampal atrophy and PVH increased as the severity ofOSAHS aggravated among these groups. Compared to primary snoring group, MoCA andMMSE scores were decreased (28.0±1.9vs24.5±2.7, P=0.000;28.7±1.3vs27.5±1.4,P=0.013), and hippocampal atrophy scores and PVH scores were increased (1.5±1.2vs2.4±1.2, P=0.007;1.6±1.8vs3.6±1.0, P=0.000) in the severe OSAHS group. The evaluations of MoCA subdomains further revealed selective reduction in visual space andexecution function and delayed memory. PVH scores and hippocampal atrophy scores werenegative correlated with the MoCA scores(r=－0.30, P=0.010; r=－0.30, P=0.006).Multiple linear regression analysis indicated that the degree of AHI and hippocampalatrophy were the main risk factors for MoCA scores (the standardized regressioncoefficient:－0.386,－0.247; P=0.000,0.020). The scores of hippocampal atrophy andPVH were positively correlated with AHI, oxygen reduction index (ODI), respiratoryrelated arousal index (RI) and negative correlated with minimum oxygensaturation(LSaO2), average oxygen saturation(MSaO2)(P＜0.05). The metabolism of lipid,coagulation function and hematokrit in patients with OSAHS were not different amongevery group, and also were not related with the changes in the structure of the brain（P＞0.05）.Conclusions The changes of MRI in hippocampus and cerebral white matter wasclosely related to cognitive dysfunction, and it may be as a objective indicator to assesscognitive function in patients with OSAHS.