Multimodal Magnetic Resonance Imaging Study Of Somatic Symptom Disorder

Somatic symptom disorder(SSD)is a common neuropsychiatric disease.SSD is characterized by extreme attention to physical symptoms,such as pain or fatigue,leading to serious emotional distress and functional problems.SSD patients have high rates of depression and anxiety,poor quality of life,frequent visits,and high medical costs.It has become one of the public health problems.The pathology of SSD is still unclear and the treatment methods are limited.Therefore,a better understanding of the pathophysiology of SSD may help to develop better diagnosis and treatment methods for these patients.Multimodal magnetic resonance imaging(MRI)to explore the functional and structural changes of the brain in patients with SSD in this research.This paper collected multimodal MRI data of 60 SSDs and some healthy controls,including resting functional magnetic resonance data(60 cases),high-resolution T1-weighted structural images(60 cases),and multi-b-value diffusion tensor imaging(DTI)(30cases).In this study,resting-state functional MRI(f MRI)was used by independent component analysis(ICA)to investigate functional connectivity(FC)changes within and across networks between patients and controls first.fractional amplitudes of low-frequency fluctuation(f ALFF)were used to detect intensities of spontaneous functional activity in networks successfully separated by ICA.The results show that the patients with SSD exhibited significantly increased FC in the left lingual gyrus within the visual network and higher f ALFF values in the cingulate cortex and precuneus within the default network.Furthermore,SSD patients showed significantly decreased FC between the default and visual networks.This may indicate an imbalance within and between networks.These decouplings are likely associated with impaired perceptual and self-conscious integration in those with the disease.Secondly,based on multi-b-value DTI,probabilistic fiber tracking was carried out to construct the brain structural network,and the network topological properties were calculated to explore whether the patients with SSD are abnormal in the brain structural network.DTI metrics were calculated and the brain structural network was constructed by the probabilistic fiber tracking method.In network efficiency,SSD patients’ local and global efficiency was significantly lower than those of healthy controls.In small-world metrics,the clustering coefficient of SSD patients was significantly lower than that of healthy controls,and the characteristic path length was significantly higher than that of healthy controls in high sparsity thresholds.With the increase of the sparsity threshold,small-worldness also showed a trend of difference.We believe that in patients with SSD,the efficiency of signal and material transmission between brain neurons was reduced,the interconnection between local regions was weakened,and the overall information integration ability of the brain was reduced,which may lead to the abnormality of self-perception and body perception function.Lastly,we examined microstructural abnormalities in the brains of patients with SSD using multi-b-value DTI to investigate the correlation between these abnormalities and clinical indicators.Compared to HCs,patients with SSD had significantly higher fractional anisotropy(FA),mean kurtosis(MK),and radial kurtosis(RK)and significantly lower mean diffusivity(MD)and radial diffusivity(RD)in the cerebellum,thalamus,basal ganglia,and limbic cortex.The FA in the left caudate and the pontine crossing tract were negatively correlated with disease duration;the MD and the RD in the genu of the corpus callosum were positively correlated with disease duration.Our findings highlight the role of the cerebellum-thalamus-basal ganglia-limbic cortex pathway,especially the cerebellum,in SSDs and enhance our understanding of the pathogenesis of SSDs.In conclusion,we found that rest-state brain function in SSD patients showed abnormality in local and FC;The structural network has been changed,while the microstructure has been changed significantly.These results provide new insights into the neural basis of SSD and will be beneficial to the diagnosis and treatment of this disease.