MRI Assessment Of Brain Gray Matter Structural Changes In Nicotine Dependent Population

Background and purposeTobacco is one of the most serious public health problems in the world today.Nicotine and other compounds will be released in the tobacco combustion process,which is the main cause of addiction,also can cause such as respiratory system,cardiovascular and cerebrovascular system diseases,and Each year,about one million people die from tobacco-related diseases.Although most smokers have a strong desire to quit smoking,most individuals who quit smoking are relapsing within a week generally.So it is important to explore the effects and mechanisms of smoking on brain structure for guiding smoking cessation.Previous studies of smoking focus on brain function,and the impact on brain structure is controversial,so understand the impact of smoking on brain structure to guide smoking cessation also has a very important significance.Voxel based morphometry(VBM)is a whole brain-based analysis technique that uses computer-based automatic processing to analyze gray matter based on the whole brain and quantify the change of local gray matter volume to accurately display brain tissue morphological changes,and then understand the brain neuronal damage.The aim of this study was to evaluation of brain structure changes in different nicotine-dependent populations by voxel-based morphological analysis.Materials and methodsIn this study,119 chronic smokers and 37 non-smoking healthy volunteers were scanned with Siemens Skyro 3.0T magnetic resonance scanner.The smokers were divided into 77 mild nicotine-dependent group(FTND<6)and 42 severe nicotine-dependent group(FTND?6).During the scanning,head were fixed,and participants were informed to follow the precautions.Subjects were routinely MRI(to exclude intracranial lesions)sequence and 3D-MPRAGE sequence.SPM8 pretreatment based on Matlab was used to analyze the data.The SPM8 software was used to analyze the independent sample t test(FWE correction,P <0.001)with the smoking group and the control group and average education years and age as covariant variables;and One-way analysis of variance was performed in severe nicotine-dependent group,mild nicotine-dependent group and control group,and then LSD was compared between the groups.The results are expressed as mean±standard deviation(x± s).The spearman correlation analysis was used to analyze the difference between smoking group,different nicotine dependent group and smoking data with SPSS 17.0.The statistical level of the statistical analysis was 0.05,and when P <0.05,the difference was statistically significant.Results1.Compared with the control group,smokers exhibited decreased GMV in bilateral thalamus,bilateral parietal lobes(right supramarginal gyrus,right postcentral gyrus,left supramarginal gyrus),the left lenticular nucleus(putamen)(FWE corrected,P <0.05,cluster size> 303voxels),and no area with elevated GMV was found.Bilateral thalamus,right parietal lobe and left lenticular nucleus GMV were significant negatively correlated with smoking index and tobacco age,and bilateral thalamus was negatively correlated with daily smoking(? = 0.05,P <0.05).2.Compared with the mild nicotine-dependent group,severe nicotinedependent group exhibited decreased GMV in left precentral gyrus(FWE uncorrected,P <0.0005,cluster size> 150voxels),and no GMV increased areawas found.The left precentral gyrus GMV was negatively correlated with smoking index and smokingage(? = 0.05,P <0.05).3.Compared with the control group,the severe nicotine-dependent group exhibited decreased GMV in right posterior cingulate cortex(FWE corrected,P <0.05,cluster size> 359voxels),and the area with elevated GMV was not found.The right posterior cingulate cortex GMV had no significant correlation with clinical behavioral data(? = 0.05,P <0.05).4.Compared with the control group,the mild nicotine dependent group exhibited decreased GMV in bilateral thalamus,bilateral supramarginal gyrus(right supramarginal gyrus,left supramarginal gyrus),and the area with elevated GMV was not found(FWE corrected,P <0.05,cluster size> 318voxels).Bilateral thalamus,right supramarginal gyrus GMV were significant negatively correlated with smoking index and tobacco years,and right thalamus was negatively correlated with daily smoking(? = 0.05,P <0.05).ConclusionsThe changes of brain structure among smokers,various levels of nicotine dependents and healthy contral mainly focused on reward related pathways and marginal systems,and part of the gray matter volume of brain regions is related to smoking behavior data.The effect and location of tobacco or nicotine is not entirely consistent among different nicotine dependence and smokers,which may indicate that there is indeed an intermediate phenotype(such as mild nicotine dependence)that is not easily found to be subtle in smokers.This study enriched smokers(Nicotine)addiction brain structure based on nicotine dependence,which could provide a strong scientific evidence for the study of long-term chronic smoking addiction.