The characteristics and determining factors of attention and short-term memory impairment in young patients with obstructive sleep apnea-hypopnea syndrome

Abstract

Objective: To explore the characteristics and determining factors of attention and short-term memory impairment in young patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). Methods: A total of 203 eligible patients with snoring were recruited for the study at Sleep Center, Second Affiliated Hospital of Soochow University from July 2016 to July 2017, and they were all monitored with overnight polysomnography(PSG), recording sleep parameters [NREM (Ⅰ+Ⅱ) sleep ratio, NREM Ⅲ sleep ratio, REM sleep ratio] and respiratory parameters (AHI, ODI, LSaO(2), TS90%, RRMAI). Based on apnea/hypopnea index(AHI), the patients were categorized into non-OSAHS group (0<AHI≤5/h), mild and moderate OSAHS group (5<AHI≤30/h), and severe OSAHS group (AHI>30/h). All patients were assessed for sleepiness and the Motreal Cognitive Assessment (MoCA) questionnaires, Mini-mental State Examination (MMSE), Epworth Sleepiness Scale(ESS), attention and short-term memory assessment which included Trail Marking Test(TMT), digit span test(DST), and Complex Figure Test(CFT). The PSG parameters, ESS scores, total MoCA scores, attention and short-term memory were compared among groups, and a multivariate logistic regression analysis was conducted to investigate the characteristics of attention and short-term memory impairment in young patients with OSAHS and their determining factors. Results: In the overall cognitive function assessment, severe OSAHS patients's MoCA scores were lower than those of the other two groups [27.0 (25.0, 28.0) vs 27.0 (26.0, 28.0) , 27.0 (26.0, 27.0) , P<0.01]. In the sleepiness self-assessment, severe OSAHS patients's ESS scores were significantly higher than those of the other groups (11.4±5.4 vs 5.3±4.5, 8.0±5.0, P<0.01) . In the attention tests, scores on the DST-D (8.1±1.1 vs 8.8±0.9, 8.5±1.0) and DST-B[5.5 (4.0, 7.0) vs 6.0 (5.0, 7.0) , 6.0 (5.0, 7.0) ] were significantly lower in severe OSAHS patients than in the other two groups (P<0.01) . In the memory tests, the re-drawing scores of severe OSAHS patients were significantly lower than those of the other two groups [23.0 (16.0, 27.0) vs 26.0 (24.0, 28.0) , 24.0 (20.0, 28.0) , P<0.01]. In the executive function tests, severe OSAHS patients spent much longer on both TMT-A (46.7±19.0 vs 40.2±17.4, 34.6±17.2) and TMT-B (76.9±32.6 vs 67.2±21.2, 58.6±27.5) than the other two groups (P<0.01). Multivariate logistic stepwise regression analysis showed that, AHI, ODI and NREM (Ⅰ+Ⅱ) sleep ratios were the independent determining factors. Conclusion: Attention and short-term memory functions of young patients with OSAHS were impaired. The severity of apnea and hypoxia, NREM (Ⅰ+Ⅱ) ratio were all determining factors.