Regional Homogeneity Applied To Evaluate Brain Functional Activity During Resting State In Addicted Male Smokers

Background Smoking and exposure to secondhand smoke are the deadly killer of human health. China is not only the largest country of producing tobacco in the world, but also the biggest country of tobacco consumption and suffering hazards of tobacco. According to 2015 Chinese adult tobacco survey, the number of smokers in China was increased by 15 million during five years, from 301 million in 2010 to 316 million in 2015. Smoking addiction is a chronic recurrent disease, its pathogenesis is associated with the mesolimbic dopamine system. In recent years, domestic and overseas scholars studied the brain structure and function of smoking addicts through resting state f MRI(functional magnetic resonance imaging, f MRI), and found that the brain structure and functional activity of smoking addicts have changed, but the part of the change is not the same.Objective To explore the changes of brain functional activity in addicted male smokers during resting state. To compare the difference of brain functional activity in addicted male smokers which have different pack years and different FTND(Fagerstr?m test for nicotine dependence)scores.Methods 37 male smokers and 37 healthy male non-smokers matched for age were recruited by advertisement to conduct the case-control study. Sociodemographic data, smoking related characteristics and functional magnetic resonance imaging(f MRI) images were collected and analyzed.Results Compared with nonsmokers, the regions including left and right frontal lobe showed decreased Re Ho in smokers, the regions including right limbic lobe, rightparahippocampa gyrus, left temporal lobe, right precuneus, right superior frontal gyrus and right middle frontal gyrus showed decreased Re Ho in smokers. Compared with light smokers(pack years ≤20), heavy smokers(pack years >20) showed Re Ho decreased in the right inferior temporal gyrus, right middle temporal gyrus, right temporal lobe/Sub-Gyral, Frontal_Inf_Orb_R(aal), right inferior frontal gyrus, right middle frontal gyrus, left middle frontal gyrus, left inferior frontal gyrus/left precentral gyrus, right superior frontal gyrus, Parietal_Sup_L(aal), right postcentral gyrus/Paracentral_Lobule_R(aal) and right medial frontal gyrus but increased in the left frontal lobe/rectal gyrus, left pons, right lingual gyrus, left cerebellum anterior lob/culmenl and left parietal lobe/Sub- Gyral. Compared with nonsevere nicotine dependent smokers(FTND ≤6), severe nicotine dependent smokers(FTND > 6) showed Re Ho decreased in the right cerebellum posterior lobe/inferior semi-lunar lobule, left postcentral gyrus and left precuneus but increased in the right insula, left inferior frontal gyrus, right middle frontal gyrus, right frontal lobe/Sub- Gyral, right limbic lobe/cingulate gyrus, left middle frontal gyrus/precentral gyrus and right medial frontal gyrus.Conclusions Smoking might lead to the changes of resting-state brain functional activity in frontal lobe, temporal lobe, and limbic lobe in smokers. The change of resting state functional activities in many brain regions may be related to the accumulative amount of nicotine intake and the severity of nicotine dependence. This study could help smokers understand smoking addiction is a brain disease so as to lay the foundation for the promotion of the health management of smoking cessation.