Research On The Resting State Brain Network Of Adolescent Smokers Based On Dynamic Functional Connection

According to statistics released by the World Health Organization(WHO)in 2019,there are already more than 1.1 billion smokers in the world.Smoking is currently the number one preventable cause of death and various diseases.If no effective interventions are taken,the number of deaths caused by smoking can be as high as 6 million each year.By 2030,smoking will cause global smoking.The death toll is estimated to be as high as 8million.Numerous previous studies have shown that the period from adolescence to adulthood is a critical period for continued brain development.During this critical period,adolescents experience a series of changes in physical,psychological and social functioning.Compared with adults,people who start smoking in adolescence are more likely to become addicted to nicotine and more likely to become lifelong smokers,because the functional structure and nervous system of the adolescent brain are not fully developed,and the brain circuits involved in cognitive control are still developing.Therefore,more attention should be paid to the study of the underlying neural mechanisms in adolescent smokers.Although great progress has been made in studying the neurocognitive function of adolescent smokers,traditional resting-state functional connectivity studies are based on the assumption that functional connectivity between brain regions is static during the scanning process of brain signals,without considering the dynamic change of functional connectivity over time.More and more studies have proved that the functional connectivity of the brain changes dynamically in the resting state,and the process in which the functional connectivity fluctuates over time is called dynamic functional connectivity.There is currently a gap in the study of dynamic functional connectivity of brain functional networks in adolescent smokers,and among all functional networks in the brain,the default mode network(DMN),executive control network(ECN)and salience network(SAN)are very closely related to smoking addiction.In this study,dynamic functional connectivity analysis methods including independent component analysis,sliding time window analysis,and K-means cluster analysis were used to investigate the dynamic functional connectivity changes between DMN,ECN,and SAN in the resting-state brains of 42 adolescent smokers and 42 non-smokers.Two-sample independent t-test was used to detect differences in dynamic functional network connectivity between adolescent smokers and non-smokers,and Mann-Whitney U test was used to detect differences in dynamic functional connectivity indicators(fraction time,mean dwell time and transition number)between adolescent smokers and non-smokers,and Spearman correlation analysis was used to evaluate relationship between different dynamic functional connectivity indicators and smoking statistics data.The results showed that compared with non-smokers,the functional connectivity within the ECN of adolescent smokers was reduced.Correlation analysis showed that fractional time and mean dwell time in dynamic functional connectivity indicators were significantly negatively correlated with the degree of nicotine dependence in smoking statistics data.From the perspective of dynamic functional connectivity,this study discusses the differences of dynamic functional connectivity between DMN,ECN and SAN in the brain of adolescent smokers and non-smokers,which can provide new insights into the mechanism of smoking addiction of adolescent smokers,and provide more reliable evidence for the study of spontaneous neural activities of brain functional network.