Convergent Findings Of Functional And Structural Alterations Within The Frontostriatal Circuits In Patients With Bulimia Nervosa: A Multimodal MRI Study

Objective:Bulimia nervosa?BN?is a common eating disorder.In recent years,several neuroimaging studies have showed structural and functional alterations within the frontostriatal circuit in individuals with bulimia nervosa,which is related to the recurrent overeating and impaired inbitory control.However,there has been no researches exploring functional connectivity?FC?and structural connectivity within the frontostriatal circuit in BN.Furthermore,studies reported inconsistent results about brain structure features of BN.We utilized resting-state functional magnetic resonance imaging,diffusion tensor imaging?DTI?and structural MRI to investigate the functional connectivity,structural connectivity and features of brain structure within the frontostriatal circuit of BN,respectively.Also,the relationship between abnormal cerebral features and the clinical data was analyzed in BN.Methods:39 first-episode and medication-naive women with BN and 36age and education-matched healthy control subjects were recruited in the study.All the participants underwent 3.0 T MRI scans,and resting-state fMRI,DTI and T1 weighted images were collected.Beyond that,neuropsychological assessments were performed,including a stop signal task,Barratt Impulsiveness Scale-11 and Eating Disorder Examination Questionnaire 6.0.We used seed-based and voxelwise functional connectivity to analyze the alterations of the synchrony between striatal subregions and the frontal cortex in BN.And probabilistic fiber tracking was used to explore the structural connectivity changes between the striatum and the frontal cortex?Based upon results of resting states fMRI?in BN.At last,voxel-based morphometry?VBM?was used to detect differences of gray and white matter volume between BN and healthy participants.In addition,correlations between abnormal functional connectivity,structural connectivity and brain volume and clinical scales in BN were analyzed.Results:1.Compared with healthy control subjects,FC between the limbic subregions of the striatum and bilateral medial orbitofrontal cortex?mOFC?and left lateral OFC in BN patients was decreased.Furthermore,FC between the rostralmotor subregions on the one hand,and supplementary motor area?SMA?/paracentral lobule,right precentral gyrus?PCG?,left dorsolateral prefrontal cortex?dlPFC?/middle frontal gyrus?MFG?,left inferior frontal gyrus?IFG?and right pars orbitalis on the other hand was diminished.In addition,we found that FC between caudalmotor subregions and SMA/paracentral lobule,right PCG,left dlPFC/MFG and IFG was decreased.All the above-mentioned results were corrected by false discovery rate?FDR?with a threshold of 0.01?FDR corrected,p<0.01,cluster size?35 voxels?.At last,reduced FC between the right cognitive subregions and left MFG,left IFG and right SMA was also detected?FDR corrected,p<0.05,cluster size?35 voxels?.Correlation analysis revealed that the FC between left rostralmotor subregion of striatum and the SMA negatively correlated to the feelings of loss of control on eating in BN patients?r=-0.504,p=0.002?.Moreover,the left rostralmotor striatum-right precentral gyrus FC and FC between the left caudalmotor subregions and SMA and between right caudalmotor subregions and right IFG in BN patients was negatively related to preoccupation with shape and weight?r=-0.418,p=0.011;r=-0.510,p=0.001;r=-0.415,p=0.012?.And the FC between the left caudalmotor striatum and SMA negatively related to eating disorder examination total scores?r=-0.458,p=0.005?.FC between the left rostralmotor striatum and the left MFG inversely related to unplanning impulsivity?r=-0.452,p=0.006?.At last,right rostralmotor subregions-right PCG FC was correlated to the duration of the disease?r=0.478,p=0.004?.2.Compared with healthy controls,structural connectivity strength between the right dorsal and media striatum and the right SMA was decreased?p<0.001?.Correlation analysis showed that structural connectivity between the right dorsal and media striatum and the right SMA correlated to stop signal reaction time?r=0.414,p=0.028?and negatively related to body mass index?r=-0.496,p=0.005?in BN.Furthermore,structural connectivity strength between the right dorsal and media striatum and the right SMA negatively related to functional connectivity strength between the left rostralmotor striatum and the SMA?r=-0.363,p=0.025?.3.Compared with healthy controls,bulimia nervosa patients exhibited reduced grey matter volume?GMV?in bilateral gyrus rectus,cerebellum/lingual gyrus,left MFG,right precuneus and left SMA and increased GMV in right pars opercularis.Besides,white matter volume in the left gyrus rectus in BN was also decreased(Alphasim corrected,p<0.05,p_voxel<0.005,cluster size?60 voxels).Correlation analyses showed that reduced grey matter volume in the left SMA of BN negatively correlated to preoccupation with eating?r=-0.405,p=0.014?.Conclusions:For the first time,results of the present study indicate that both functional and structural connectivity within the frontostriatal circuits is aberrant in female bulimia nervosa patients.In addition,gray and white matter volume within the frontostriatal circuits was aslo found in BN patients.And these functional and structural alterations are related to impulsivity and severity of symptoms in BN.This study increases our knowledge of changes that occur in the brain of BN subjects and highlights the pathophysiology of frontostriatal circuitry in impaired inhibitory control and high impulsivity in BN.And the specific role of functional and structural alterations within the frontostriatal circuit in the pathological mechanisms of BN remains to be further investigated.