Structural,Functional MRI And MR Spectroscopic Studies Of Betel Quid Dependence

Betel quid(BQ)ranked the fourth most frequently consumed psychoactive substance around the globe,following only alcohol,nicotine,and caffeine in prevalence.BQ chewing is an important behavior from a public health perspective because it is associated with a variety of health issues,most notably oral cancer,esophageal cancer,liver cancer and cervical cancer and precancerous conditions such as leukoplakia and oral submucous fibrosis.Consequently,BQ has been categorized into a Group 1 carcinogen by the International Agency for Research on Cancer.The addictive characteristicsof betel quid dependence are in line with the drug addiction summarized by World Health Organization:?desire and compulsion to seek and take the drug and loss of control in limiting intake?the increasing trend of drug doses(tolerance);? the psychological and physiological dependence of addictive substances;?having a higher risk on individuals and society.Therefore,betel quid dependence in line with the Diagnostic and Statistical Manual of Mental Disorders(DSM-IV;American Psychiatric Association,2000)and the ICD-10(World Health Organization,1992)belongs to the category of substance dependence,the same as tobacco and alcohol dependence.BQ use is associated with a dependency syndrome,which comprises increased concentration,mild euphoria,relaxation,postprandial satisfaction and a withdrawal syndrome associated with insomnia,mood swings,irritability and anxiety,the severity of which can be compared with that of amphetamine use.A few studies have assessed BQ dependence using adapted versions of dependence scales that were designed for substances other than BQ such as opioids or tobacco.Lee in Taiwan recently developed,and provided initial validation for,the first instrument designed specifically for measuring BQ dependence:the Betel Quid Dependence Scale(BQDS).BQDS is the first instrument designed specifically for measuring BQ dependence.The BQDS is comprised of three factors:"physical and psychological urgent need," "increasing dose," and "maladaptive use".The BQDS have assessed BQ dependence using approaches based upon the DSM-IV and ICD-10.The BQDS was found to have good internal consistency(a=.92)and construct validity.Although BQ is chewed by approximately 600 million people globally,its use is concentrated in South Asia,Southeast Asia,and Pacific islands.From prevention and treatment point of views,it is important to understand such reasons so that strategies may be developed to help individuals overcome an addiction.However,to date,most research on BQ chewing has been limited to epidemiological and biological investigations.Limited research has been conducted to understand the behavioral and psychological factors that lead individuals to initiate and/or maintain BQ chewing.With the rapid development of magnetic resonance imaging technology,research on substance dependence transition from the macro to the micro structure,metabolism and function of research,so that medical imaging diagnostic mode from the traditional morphology,gradually turned to modern imaging both with morphology and function.Functional magnetic resonance imaging is a non-invasive detection technology by far the most commonly used,with its high spatial and time resolution,non-invasive,non-radiation damage and can be repeated to detect in vivo,etc.Functional magnetic resonance imaging technology has been widely applied to the study of substance dependence related brain structure,metabolism and function.Voxel-based morphometry(VBM)can objectively,automatic detection the brain structure differences in the whole brain scope,no prior knowledge,has certain advantages in terms of microstructure research to quantify analysis of potential abnormal brain morphological.Pathological changes in the baseline brain can be evaluated using Resting-state functional MRI(Resting-state fMRI,rs-fMRI)without task design,which have been extensively used to study cognitive neuroscience and neuropsychiatric disorders.Through various kinds of data analysis methods,we are able to take advantage of spatial and temporal characteristics of brain activity.Regional homogeneity(ReHo)can observe the local BOLD activity of brain synchronization;low-amplitude(amplitude of low frequency fluctuation,ALFF)may reflect the individual elements from an energy point of view in the resting state of spontaneous activity level.ReHo and ALFF methods are based on whole-brain voxel statistical study,the combination of these two methods can be more comprehensive understanding of the characteristics of brain activity in the resting state.MRS(magnetic resonance spectroscopy,MRS)can noninvasively detect and quantify the living brain tissue major metabolite.Short TE(TE=30ms)two-dimensional multi-voxel 1H-MRS analysis technology can better display inositol and glutamic acid complexes,as to more comprehensive understand human physiological changes at the molecular level.So make more definitive conclusions,including early diagnosis,prognosis,and differential diagnosis,tracking the effect of the disease,etc.The recent results of imaging studies indicate the prefrontal cortex,ventral tegmental area;nucleus accumbency,insula and so many brain districts may have the structural and functional damages in substance dependence patients,such as nicotine,alcohol,cocaine,heroin,etc.These studies lead to a more objective and scientific understanding of substance dependence.However,due to the geographical restrictions and defect awareness on betel quid dependence,there haven't had studies reported brain mechanisms of betel quid dependence.Limited research has been concentrated on pharmacology and behavioral research.So,what kind of impact betel quid dependence on the brain structure,functionandmetabolism of the relatively weak addictive substance?Betel quid acting on brain regions in the brain and "illegal addictive substances" are the same?The objectives of this study is to explore different aspects of brain structure,function andmetabolism in betel quid dependencepatients using different Functional MRI analysis tools,and its relationships with the severity and duration of betelquiddependence were analyzed.Further explore the neural mechanisms to improve our understanding of betel quid dependence,provide a scientific basis for intervention and treatment of betel quid dependence.There are three parts in this dissertation.Part I.Gray matter abnormalities associated with betel quid dependence:a voxel-based morphometry studyObjective:Betel quid dependence(BQD)patients have a cluster of cognitive,behavioral,and physiological symptoms which are associated with structural abnormalities in brain gray matter.In this study we will assess the volumetric abnormalities of grey matter in BQD and investigate the correlations between brain structural changes with Betel Quid Dependence Scale(BQDS)and duration.Methods:Persons with usage of BQ at least one day at a time for no less than 5 year and BQDS>4 without tobacco or any other drug addiction were categorized as "Betel Quid Dependence".Persons without usage of BQ,areca nut and tobacco(in all forms)were defined as "healthy control".A T1-weighted structural image with high resolution was obtained with a MPRAGE sequence.The VBM8 tool-box with default parameters running in the SPM8 software was used to conduct gray matter(GM)analysis.The non-linear constituents originated from the normalization matrix multiplied the analysis for the purpose of sustaining actual GM values locally(coordinated GM volumes).Independent samplest tests were used to analyze smoothed GM,with gender and age as nuisance covariates.The GM values on average revealed by VBM for all voxels in abnormal regions were extracted and correlation was made with BQDS,BQD duration,SDS in BQD subjects with Pearson correlation analysis,in order to detect any connection between structural abnormalities and characteristics of addiction.Results:At last,33 BQD volunteers and 32 HC individuals successfully obtained 3D structural imaging recruited from a residential area of Wanning City of Hainan province,China were included.The average age of the BQD sample was 46.7±9.4 years;The BQD group was 72.7%male,and had completed 12.3±2.7 year's education;Individuals indicated that they had been chewing BQ with dependency syndrome for a mean duration of 20.6±6.9 years(range 7 to 31 years),a mean BQDS of 10±3.4(range 5 to 16)and consumed an average of 342±106g/day BQ(range 200 to 500 g/day)daily.BQD chewers placed BQ in their mouth for an average of 7.6±2.4 minutes(range3 to 12)before spitting-out the remnants.There was no difference for the age,sex,education years,monthly income,alcohol last 30 days and SAS between the BQD patients and HC(P values>0.05);however,the BQD patients had a lower SDS score than HC(t=2.385,P=0.020).Compared with HC,BQD patients exhibited declined GM volume in midbrain,right medial prefrontal cortex(mPFC),bilateral dorsolateral prefrontal cortex(dlPFC),right superior temporal gyrus(STG),and greater volume in right hippocampal and right precuneus(All P values<0.05,AlphSim corrected).Gray matter volumes of the left DLPFC,the right rACC indicated a negative association with duration of BQD(r1=-0.506,P1=0.003;r2=-0.541,P2=0.001);when finding association between the BQD score and GM segmentations,a negative correlation in the midbrain volume in BQD patients was found(r3=-0.427,P3=0.013).No correlation was found between other gray matter volume and clinical indexes,including BQD scores,illness duration in BQD patients.Conclusions:It is suggested in our study that the alterations of brain structure exist in BQD patients and dysfunction of the reward system,cognitive system and emotion system may be a neurobiological basis for BQD patients.Overall,the GM volume alterations in current research demonstrated a microstructural change in the brain,which further promoted our understanding of BQD.Also,VBM is an effective tool for in vivo investigation of gray matter alterations in patients with BQD.Part II.Altered spontaneous brain activity in betel quid dependence:a resting-state fMRI studyObjective:Regional homogeneity(ReHo)and the amplitude of low-frequency fluctuation(ALFF)are two approaches to depicting different regional characteristics of resting-state functional magnetic resonance imaging(RS-fMRI)data.Whether they can complementarily reveal brain regional functional abnormalities in betel quid dependence(BQD)remains unknown.This study used a resting-state fMRI to investigate changes in spontaneous brain activity among patients with betel quid dependence and to determine the relationship of these changes withBetel Quid Dependence Scale(BQDS)and duration.Methods:MRI data were obtained on a Siemens 3T MRI scanner.In this study,we applied ReHo and ALFF to 33 betel quid dependence patients and 32 age-,sex-and education-matched healthy controls using whole-brain voxel-wise analysis to represent spontaneous brain activity.Correlation analyses were conducted in the BQD group to investigate the relationship between the regional spontaneous brain activity measured by the two approaches and the Betel Quid Dependence Scale(BQDS)and duration of BQD.Results:Compared with healthy control subjects,patients with BQD had significantly decreased ReHo values in left fusiform,right rectus and bilateral anterior cingulate cortex(ACC),increased ReHovalues in the left cerebellum posterior lobe,middle temporal gyrus,precentral,paracentral lobule and right superior temporal gyrus,inferior temporal gyrus,inferior occipital gyrus,precentral.Patients with BQD had significantly decreased ALFF values in left fusiform,medial prefrontal cortex;right paraHippocampal,anterior cingulate cortex(ACC)and bilateral dorsolateral prefrontal cortex;increased ALFF in the left precentral,superior temporal gyrus,paracentral lobule;and right calcarine,bilateral lingual.Right anterior cingulate(ACC)ReHo values were negatively correlated with BQDS and duration in the BQD group(r1=-0.476,PI=0.005,r2=-0.526,P2=0.002),left ACC ReHo values were negatively correlated trend with BQDS in the BQD group(r3=-0.314,P3=0.075),right ACC ALFF values were negatively correlated with BQDS in the BQD group(r4=-0.471,P 4=0.006),leftsuperior temporal gyrusALFF values were positively correlated with duration in the BQD group(r5=0.358,P5=0.041).Conclusions:Combination of the ReHo and ALFF may yield a more comprehensive spontaneous brain activity for BQD,which may provide insights into the neurological pathophysiology underlying BQD-associated cognitive and impulsive control decline,also support the theory of reduction the monitoring function of the BQD patients.Spontaneous brain activity changes in right ACC may be as a stable functional imaging quantitative index of betel quid dependence severity.The detailed mechanisms,implications of these brain activities and networks exhibiting changes will require further investigation.Part?.Neurochemical evaluation of brain function with multivoxel 1H magnetic resonance spectroscopy in patients with betel quid dependenceObjective:To assess the role of short echo time(TE=30ms)multivoxel 1H magnetic resonance spectroscopy(MRS)in the detection of changes in metabolite levels of the gray matter of betel quid dependence patients.In addition,the correlations between brain metabolite levels and Betel Quid Dependence Scale(BQDS)and duration were assessed for revealing the neurobiological basis of betel quid dependence.Methods:MRS was performed in 33 betel quid dependence patients and 32 age-,sex-and education-matched healthy controls.A sagittal T1-weighted structural image with high resolution was obtained with a MPRAGE sequence for voxel localization.A standard 2D-multivoxel MRS(CSI)was used for measuring a transverse volume of interest located at anterior cingulate allowing for direct comparison of the metabolites in grey matter brain tissue.Choline/Creatine(Cho/Cr),N-acetyl aspartate/Creatine(NAA/Cr),myo inositol/Cr(MI/Cr)?glutamic acid salt mixture/Cr(Glx/Cr)ratios were examined at bilateral anterior cingulate(ACC),medial thalamus,lenticular nucleus and insular lobe.Statistical analyses were done using independent samples t-test.Pearson correlation analysis was used to analyze the relationship between altered metabolite ratios and BDQS and duration in BQD patients.Results:In BQD patients,NAA/Cr ratios were found to be significantly decreased compared to healthy controls in bilateral ACC(Lelf,t=2.543,P=0.013,Right,t=2.908,P=0.005),medial thalamus(Lelf,Z=2.016,P=0.044;Right,t=2.119,P=0.038),lenticular nucleus(Lelf,t=2.129,P=0.037;Right,t=2.391,P=0.020)and insular lobe(Lelf,t=3.080,P=0.003;Right,t=2.147,P=0.036)and right ACC(t=2.908,P=0.005),left insular lobe(t=3.080,P=0.003).Cho/Cr ratios were found to be increased compared to healthy controls in bilateral ACC(Lelf,t=2.263,P=0.021;Right,t=2.267,P=0.027).MI/Cr ratios were found to be increased compared to healthy controls in left ACC(t=2.399,P=0.019),bilateral medial thalamus(Left,Z=2.218,P=0.020;Right,Z=2.830,P=0.005),left lenticular nucleus(Z=2.729,P=0.006)and bilateralinsular lobe(Lelf,t=5.430,P=0.000;Right,Z=2.781;P=0.005).Glx/Cr ratios were found to be increased compared to healthy controls in bilateral ACC(Left,t=3.227,P=0.002;Right,Z =2.505,P=0.012)and bilateral insular lobe(Lelf,Z=2.777,P=0.005;Right,t=2.049,P=0.045),left medial thalamu(Z=2.484,P=0.013).Significant negative correlations were found between NAA/Cr ratios and BQDS,duration(r1=-0.387,P1=0.026;r2=-0.468,P2=0.006)in right ACC,Significant positive correlation was found between Glx/Cr ratios and BQDS(r3=0.373,p3=0.033)in right ACC,Significant negative correlation was found between NAA/Cr ratios and duration(r4=-0.533,P4=0.001)in left ACC,for BQD patients.Conclusions:The metabolite abnormalitiesin ACC,medial thalamus,lenticular nucleus and insular lobein BQD patients are consistent with prior observations of neuronal damage inpharmacology study on betel extraction.Multivoxel 1H-MRS is a useful tool for evaluating major changes in metabolite levels which can reveal the reward,executive and emotional dysfunction basis of BQD,the severity of the addiction may be effectively evaluated by Glx/Cr ratios in ACC.The results of this study combined with the changes of volume of gray matter,spontaneous brain activityin BQD patients,provide a scientific basis for the clinical diagnosis,treatment and prognosis of BQD.