| Obstructive sleep apnea(OSA)refers to a group of clinical symptoms that is repeated transient and reversible upper respiratory tract stenosis or obstruction during sleep,which causes hypoventilation or apnea,accompanied by snoring and excessive daytime sleepiness,leading to systemic dysfunction of multiple organs and systems.The guidelines pointed out that the main risk factors of the disease included age,gender,obesity,smoking and drinking history,upper airway anatomical abnormalities,etc.the most common risk factors were middle-aged overweight or obese men,and there were significant differences in weight and gender.The clinical symptoms include recurrent apnea and snoring in the sleep process,sleep structure disorder,abnormal awakening,obvious daytime sleepiness and so on.In severe cases,there are psychological,intellectual and behavioral abnormalities.According to the guidelines,patients' condition was diagnosed and graded according to AHI and SaO2 combined with clinical symptoms.In the study on cognitive impairment of patients with OSA,it was found that the severity of cognitive impairment was closely related to AHI.At the same time,the characteristics of the impairment were different between different age groups and different genders.According to cognitive psychology,cognitive activity is the process of information processing,which includes feeling,perception,memory,thinking,attention and other psychological activities.The mechanism of cognitive impairment in patients with OSA is very complex.Scholars believe that it must be caused by a variety of reasons,among which repeated intermittent hypoxia during sleep and sleep structure disorder are two important mechanisms leading to cognitive impairment.Chronic hypoxia for a long time can cause ischemia and hypoxia damage to multiple organs,especially the central nervous system.Sleep structural disorders often show sleep problems such as fragmentation of sleep,decrease of effective sleep time,increase of arousal times and decrease of deep sleep.Combined with other reasons,patients will gradually appear a series of clinical symptoms associated with cognitive impairment,such as daytime sleepiness,decreased alertness,attention disorder and so on.In cognitive activities,attention function is not an independent psychological process,but a special psychological phenomenon accompanied by other psychological activities.It runs through the psychological process and plays a role in maintaining direction.The mechanism of attention should be evolved by human ancestors to defend against the invasion of wild animals and enemies in dangerous natural environment.Human brain receives information from outside through all kinds of sensory organs.The attention function helps people select useful information for processing and eliminate the interference of useless information.This psychological process of information processing reflects two basic characteristics of attention "directivity and concentration".These two characteristics need to be closely related and cooperate with each other,so that the selected information can be effectively recorded and processed.In the study of attention function,attention is defined as a complex functional system including many components.Researchers use various means to evaluate attention function.Among them,the most convenient and practical assessment scales are various comprehensive cognitive assessment scales including attention,such as MMSE and MoCA.There are also scales focusing on attention designed according to it's characteristics,such as Continuous Performance Test(CPT),Stroop Color-Word Association Test,etc.However,these tests are considered to evaluate only part of the attention function.Posner et al.proposed the theory of attention function network,while Professor Fan et al.designed a behavioral test named ANT according to the theory,which can evaluate the attention function relatively comprehensively.With the development of neuroelectrophysiological technology,ERP has been widely used in practice as a relatively objective evaluation method to reflect cognitive function.P300 is recognized as an objective biological index,and is considered to be the most closely related to attention.P300 can be induced only in the condition of attention,but not in the condition of non attention.For mild and subclinical cognitive impairment,ERP is more sensitive index than the traditional neuropsychological scale test.Although previous clinical studies focusing on attention have found that many diseases may lead to attention impairment,there are relatively few systematic studies on the impairment of attention function in patients with OSA.The relevant research results support that hypoxia or sleep disorder will lead to a decline in the efficacy of attention function.These conclusions support the certainty of attention impairment in patients with OSA.At present,it is generally accepted that OSA can cause cognitive impairment.But,What are the main characteristics of cognitive impairment in patients with OSA?Which sub items of cognition are the main components of cognitive impairment?Is cognitive impairment mainly due to impaired attention function?What is the impairment of visual attention network function in patients with OSA?Is the impairment a whole or a part of attention network system?What are the temporal characteristics of visual attention impairment in patients with OSA?Is the attention impairment more severe in voluntary attention or non-voluntary attention?These problems are still the contents of the consensus debate,we will study the above problems through this experiment.Chapter ?Cognitive dysfunction and its characteristics in patients with obstructive sleep apneaObjective:To confirm the cognitive impairment in patients with OSA,and clarify that cognitive impairment in patients with OSA is a kind of mild cognitive impairment with attention as the main part.Methods:43 patients with OSA and 26 healthy volunteers were recruited in this study.All subjects were monitored and evaluated by PSG for one night,and the subjects were grouped according to AHI.The subjects were asked to go to bed before 10:00 p.m.and wake up at 6:00 a.m..The body mass index,blood pressure before and after sleep,AHI and the lowest oxygen saturation at night were recorded.On the second day after PSG monitoring,all the volunteers who sleep more than 6 hours began to evaluate the MMSE and MoCA in an independent and quiet room at 10:00 a.m.,and completed the ESS,SDS and SAS.SPSS 20.0 software(Chicago,Illinois,USA)was used for statistical analysis.Results:There was no significant difference in gender,age and education years in demographic data(p>0.05).BMI,BP,SaO2 nadir,AHI,ESS,SDS,SAS,MMSE,MoCA total score of the three groups were statistically significant(p<0.05).The results of pairwise comparison showed that BMI,CBP,BBP,MBP,AHI,SAS of moderate-severe group were significantly higher,while SaO2 nadir,MMSE and MoCA scores were significantly lower(p<0.05).The difference was statistically significant between the mild group and the normal group in SaO2 nadir and SAS(p<0.05).The ESS score of normal group was significantly lower than that of OSA group(p<0.05),but difference between two groups of OSA was no significant.The difference of SDS score between moderate-severe group and normal group was significant(p<0.05).There were significant differences in visual space,attention and delayed memory among three groups in MoCA(p<0.05).Pairwise comparison showed that the scores of moderate-severe group were significantly lower than those of other two groups(p<0.05),but there was no significant difference between mild group and normal group.Conclusion:Patients with OSA have overweight,high blood pressure,serious daytime sleepiness and emotional changes.There are obvious cognitive impairment in patients with OSA,among which moderate to severe patients have the most severe cognitive impairment,while mild patients don't have obvious cognitive impairment.Moreover,the cognitive impairment of patients is characterized by impairment of attention,memory and visuospatial function.Chapter II Effect on attention network test in patients with obstructive sleep apneaObjective:To determine the impairment of attention function in patients with OSA,and confirm the impairment of attention network function in patients with OSA is a global network damage or a sub network impairment.Methods:30 patients with OSA and 26 healthy volunteers were recruited in this study.All subjects were monitored and evaluated by PSG for one night,and the subjects were grouped according to AHI.The subjects were asked to go to bed before 10:00 p.m.and wake up at 6:00 a.m..The body mass index,blood pressure before and after sleep,AHI and the lowest oxygen saturation at night were recorded.On the second day after PSG monitoring,all the volunteers who sleep more than 6 hours began to evaluate the ANT in an independent and quiet room at 10:00 a.m.,and completed the ESS,SDS and SAS.SPSS 20.0 software(Chicago,Illinois,USA)was used for statistical analysis.Results:the results of PSG showed that SaO2 nadir of OSA group was significantly lower than that of control group,while AHI was significantly higher(p<0.01).There were significant differences in BMI,BP,ESS and SAS scores between the two groups(p<0.01),but there was no significant difference in SDS score.According to the statistical results of the average response time in two groups to three types of target stimuli(consistent,inconsistent and neutral)under the condition of four cues(none,central,bilateral and spatial),the results showed the main effect of group was significant(p<0.01),and the reaction time(RT)of OSA group was longer;the main effect of cue was significant(p<0.01),and the RT was the longest under the condition of no hint,and the shortest under the spatial cue.The main effect of flanker was significant(p<0.01),and the RT under inconsistent conditions was increased significantly,which was longer than that under neutral conditions or consistent conditions,but the difference between latter two conditions was not significant.OSA group was significantly prolonged compared with the control in total RT(p<0.05),but was not significant lower in the accuracy.In attention sub network function,the effect value of alerting network was significantly lower than that of control group,while the effect value of executive control network was significantly longer(p<0.05),while the effect value of orienting network between groups had no significant difference(p>0.05).Conclusion:patients with OSA do have attention deficit.When there is no clue,patients with OSA respond most slowly under the condition of inconsistent flanker type.The attention impairment is mainly characterized by the impairment of alerting and executive control.Chapter III Visual attention impairment in patients with obstructive sleep apnea:An event-related potential studyObjective:To evaluate the electroencephalogram(EEG)of patients with OSA in the state of non-voluntary attention and voluntary attention,and analyze whether the EEG changes are characterized by the change of orientation response represented by P3a or the change of focused attention represented by P3bMethods:26 patients with OSA and 23 healthy volunteers were recruited in this study.All subjects were monitored and evaluated by PSG for one night,and the subjects were grouped according to AHI.The subjects were asked to go to bed before 10:00 p.m.and wake up at 6:00 a.m..The body mass index,blood pressure before and after sleep,AHI and the lowest oxygen saturation at night were recorded.On the second day after PSG monitoring,all the volunteers who sleep more than 6 hours began to evaluate the visual oddball paradigm of ERP in an independent and quiet room at 10:00 a.m.,and completed the ESS,SDS and SAS.SPSS 20.0 software(Chicago,Illinois,USA)was used for statistical analysis.Results:P3a and P3b potentials were induced in both groups.In control group,the amplitude of EEG collected by CZ and PZ electrodes was higher than that of FZ,while the amplitude of P3a and P3b in OSA group was significantly lower than that in control group,and the amplitude of P3a in FZ and PZ decreased significantly.The latency of P3a and P3b was significantly prolonged in OSA group,and both of them were significantly prolonged at PZ position.The results of correlation analysis showed that the changes of P3 were closely related to PSG and emotional scores.The amplitude changes of P3a and P3b were negatively correlated with AHI,positively correlated with SaO2,and the changes of P3b latency were positively correlated with AHI.Conclusion:The visual non-voluntary attention and voluntary attention function of patients with OSA are impaired,which leads to the decrease of the ability of perceiving the emergency and the speed of visual information processing. |
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