The Impact Of Altitude Hypoxia And Smoking On Cognition And The Improvement Effect Of Oxygen Intervention

High-altitude hypoxia exposure can negatively affect cognitive function,and severe nicotine dependence can also lead to cognitive dysfunction,but the superimposed effects and mechanisms of the effects of high-altitude hypoxia exposure combined with nicotine dependence on basic cognitive function are unclear.The purpose of this study is to clarify the effects of high-altitude hypoxia and nicotine factors on individual cognition and the possible physiological mechanisms,and to try to improve the adverse effects of hypoxia combined with nicotine dependence through oxygen intervention.Methods:In this study,adults(n=300)living at an altitude of 3650m for one year were recruited for data collection in blood physiology and behavioral experiments,and questions were explored through four studies.Study 1:To explore the differences in general physiological characteristics and cognitive function of niacin-dependent individuals in a high-altitude environment,150 males(M±SD=23±2.01)at high altitude were recruited for this purpose,and the subjects were divided into three groups based on their level of niacin dependence:severe,mild and no dependence,and blood and niacin dependence level scales and cognitive behavioral data were collected to compare the differences between the groups.Study 2:To confirm that hypoxia causes increased cognitive impairment in the smoking group,hypoxic adaptations were added to the experiment,so 99 nicotine dependent subjects(M±SD=20±1.21)above mild level were screened in Study 1 subjects to investigate the differences in cognitive function between different hypoxic adaptations on nicotine-dependent subjects.Study 3:To analyze the original sample of150 people(M±SD=22±2.41)on the basis of Studies 1 and 2 to explore the underlying mechanism of hypoxia and nicotine affecting cognitive function and to develop a model.Study 4:To investigate whether oxygen intervention can improve the cognitive impairment of nicotine dependent subjects in high altitude environment,a group of 150 male subjects(M±SD=21±1.73)with mild nicotine dependence or above were recruited and divided into experimental and control groups.The experimental group was subjected to oxygen intervention for twenty days,and the cognitive function of both groups was measured before and after the intervention to investigate the improvement effect of oxygen intervention on the cognitive function of nicotine dependent subjects under hypoxia.Results:The results of Study 1 found longer flanker inconsistency task reaction times in high nicotine dependent individuals than in nonsmokers(F(3,142)=3.792,p=0.025).Study 2 results found that flanker task reaction time was positively correlated with hypoxic adaptation in a nicotine-dependent population,and that response times to flanker consistent and inconsistent tasks were higher in severely nicotine-dependent individuals with poor hypoxic adaptation than in severely nicotine-dependent individuals with good adaptation(F(3,90)=3.628,p<0.05,η_p~2=0.108)and higher than in mildly nicotine-dependent individuals with poor hypoxic adaptation(F(3,90)=3.351,p<0.05,η_p~2=0.100).Study 3 developed a mediational model with modulation and found that erythrocyte pressure volume played a fully mediated role in the relationship between hypoxic adaptation and cognitive tasks and was modulated by nicotine levels(Effect=-0.987,SE=0.052,t=-18.843,p<0.001).Study 4 found that the oxygen intervention improved cognitive function in mild and above nicotine dependent individuals by improving the level of hypoxia,especially in flanker congruent(F(2,97)=6.669,p=0.042,η_p~2=0.065)and incongruent tasks correctness(F(2,97)=5.126,p=0.041,η_p~2=0.100),which was higher in the hyperbaric group than in the non-oxygenated group.Conclusions and significance:Ultimately,we found that niacin dependence in an altitude environment affects individual performance on cognitive function tasks,and the more severe the degree of niacin dependence the more severe the impairment in cognitive function,and oxygen intervention can improve this cognitive impairment;erythrocyte pressure volume mediates between hypoxia adaptation and flanker task reaction time,and is modulated by the level of niacin dependence.This is the first time that oxygen intervention has improved cognitive function in niacin-dependent individuals in a high-altitude environment,which provides new ideas for providing individual hypoxia adaptation protocols or improving niacin impairment in humans.Further oxygen dose-effect experiments can be conducted to explore more suitable clinical protocols for nicotine dependent people,to help smoking people living in the plateau to develop good living habits and to guarantee individuals to better adapt to the plateau environment.