Study On Spontaneous Brain Activity Of Patients With First-episode Obsessive-compulsive Disorder Based On Dynamic And Static Amplitude Of Low Frequency Fluctuation

Background and purposeObsessive-compulsive disorder(OCD)is one of the common chronic and refractory mental disorders with a decreasing course and high disability rate.Patients mainly with repeated,difficult to control the obsessive thinking or compulsive behavior as the main clinical manifestations,on the patient’s daily life and social function caused a serious impact,to the society and personal family heavy economic and psychological burden,so it is urgent to find the etiology and pathogenesis of obsessive compulsive disorder.In recent years,resting-state functional magnetic resonance imaging(RS-fMRI)has become a popular technique in the field of neural research.RS-fMRI is used to obtain the changes of brain neuron activity through Blood oxygenation level dependent(Bold)signals.Among them,indicators such as Amplitude of low frequency fluctuation(ALFF),Regional homogeneity(Reho)and Functional connectivity(FC)are widely used,which can provide information of spontaneous brain activity and connectivity between brain regions.In this study,the dynamic and static low frequency amplitude was analyzed to discuss the changes of spontaneous brain activity in the resting state of first-episode untreated OCD patients,and the relationship between the dynamic and static low frequency amplitude and the severity of clinical symptoms of OCD patients.Materials and methods1.Subjects:A total of 80 first-episode untreated OCD patients(41 males,39 females,average age 24.21±8.89 years)and 100 healthy controls(49 males,51 females,average age 23.26±5.28 years)were enrolled in this study.General data,clinical scale and magnetic resonance images were collected for all subjects.All images were collected using a 3.0T magnetic resonance scanner(GE Discovery750)in this study.Before the scan,the patient’s head was fixed with a foam pad,and the patient was instructed to stay awake and relaxed during the scan.BOLD MRI was performed after routine head scan to confirm that the patient had no organic brain lesions.2.Experimental steps:DPARSFA software based on Matlab platform was used to preprocess RS-fMRI data,and subjects with head movement parameter>2mm or rotation angle is greater than 2 degrees were removed.After preprocessing,DynamicBC software was used to further calculate the dynamic static ALFF value.3.Statistical analysis:SPM12 software was used to conduct two independent sample t tests on the dynamic and static ALFF values of the smoothing patient group and the control group,and gender,age,years of education and average frame displacement were removed as covariables.SPSS21.0 software was used to analyze the correlation between dynamic and static ALFF values and the severity of clinical symptoms in the patient group.Results1 Analysis results of general clinical dataThere were no statistical differences in age(24.21 ±8.89,23.26±5.68),years of education(11.91±3.07,12.7±3.8)and sex distribution between patients and control group(P>0.05).2 Dynamic ALFF analysis results between groupsIn the resting state,two clumps with significantly higher dynamic ALFF values were found in the OCD patient group compared with the normal control group,among which the brain regions involved were distributed in the right hippocampus and the right superior marginal gyrus.No brain regions with decreased dynamic ALFF values were found.3 Static ALFF analysis results between groupsCompared with healthy controls,the static ALFF values of the right superior marginal gyrus in the OCD patients group were significantly increased,and the static ALFF values of two masses were also significantly decreased,including bilateral paracentral lobule,left lingual gyrus,and bilateral cerebellum.4 Correlation analysis between dynamic and static ALFF difference brain regions and clinical scales in patients with OCDThe results showed that the dynamic ALFF value of the right superior margin gyrus of OCD was positively correlated with the obsessive thinking factor score(r=0.257,P=0.022).No correlation was found between the static ALFF values of different brain regions and the clinical scale scores.Conclusions1.Patients with first-episode untreated obsessive-compulsive disorder(OCD)have abnormal spontaneous brain activity,including brain regions with enhanced activity and brain regions with reduced activity,suggesting that the change of internal brain activity is one of the pathogenesis of OCD.2.The enhancement of spontaneous brain activity in the right superior marginal gyrus in the patient group may be related to cognitive function defects such as attention disorder and thinking conversion disorder in the patients with obsessives disorder.