Effect Of Baduanjin On The Olfaction Function In The Elderly And Its Mechanism

The smell of human being seems to be a "marginal sense" to healthy individuals and is rarely taken seriously by individuals,but it is very important to our survival in many ways.Human can sense thousands of odors,including those associated with hazards such as natural gas leaks,fires,and spoiled food,as well as our daily meals,greatly affects our quality of life.With the increase of age,the olfactory function and olfactory-related brain regions of the elderly will show a trend of decline,which brings great inconvenience to the life of the elderly.Previous studies have generally adopted horizontal research to compare the relationship between exercise and olfaction,and mostly in the behavioral level.Few studies have longitudinally explored the behavioral performance and mechanism of the impact of exercise on olfaction.Therefore,this study aims to use f MRI technology to further explore the positive effects of 24-week Baduanjin intervention on olfactory behavior,olfactory bulb volume,activation of olfactory key brain regions,and functional connectivity,and to clarify the causal relationship between exercise and olfaction.There are five studies and six experiments in this study,and the research was conducted from three aspects: First,explored the difference of olfactory performance and its mechanism in elderly groups with different exercise habits using horizontal method(Study 1,Experiment 1);Secondly,on the basis of Study 1,current research further explored the effect of Baduanjin on olfactory performance(Study 2,Experiment 2)and the improvement effect on the volume of the olfactory bulb(Study3,Experiment 3),and then explored the positive effects of Baduanjin on the activation of the olfactory cortex and brain functional connectivity in the resting state(Experiment 4)and task state(Experiment 5)using f MRI;Thirdly,using Pearson correlation analysis to explore the relationship between olfactory behavioral performance and olfactory structure/brain functional connectivity(Study 5,Experiment 6).The results showed that:(1)Baduanjin exercise can effectively improve the olfactory performance of the elderly group,including olfaction threshold and olfactory discrimination.However,the effect of Baduanjin on olfactory identification has different results in Study 2 and Study 3.Study 2 found that Baduanjin significantly improved the subjects’ olfactory identification,while study 3 found that there was no significant difference in olfactory identification between the intervention group and control group before and after the intervention;(2)Baduanjin significantly increased the olfactory bulb volume of the elderly;(3)Baduanjin reduced the activation of orbitofrontal cortex and dorsolateral prefrontal cortex in resting state,and enhanced the Regional Homogeneity of these two brain regions;(4)In task state,in addition to reducing the activation of the orbitofrontal cortex and the dorsolateral prefrontal cortex,Baduanjin also reduced the activation of the thalamus and cerebellum,while strengthening functional connection in the limbic system,orbitofrontal cortex and cerebellum;(5)The performance of olfactory is significantly related to the structure of the olfactory bulb and the functional connectivity of the brain.The correlation between the olfactory threshold score and the volume of the olfactory bulb is higher than that of the olfactory discrimination score and the olfactory identification score.Therefore,this study suggested that Baduanjin effectively improved the olfactory performance of the elderly population,increase the volume of the olfactory bulb,and reduced the activation of key olfactory brain regions by increasing the Regional Homogeneity.Moreover,a significant correlation between olfactory behavioral performance and olfactory bulb structure / functional connectivity was found.