A FMRI Study Of Alterations Of Rest Brain Network In Patients With Hypothyroidism

Objectives:Thyroid hormones(THs)are important for the normal function of the human brain.It is still unclear whether the pathophysiology of hypothyroidism is associated with neuropsychiatric disorders.This study combined the voxel-wise functional connectivity density(FCD)and ROI-based functional connectivity(FC)obtained by resting-state blood oxygen level dependent fMRI to investigate the brain functional changes in patients with hypothyroidism,and explored the relationships among neuropsychiatric disorders,spontaneous brain resting activities and abnormal thyroid hormone level.Subjects and methods:We recruited 30 subjects totally in this study,using fasting elbow vein blood sample to measure the serum thyroid hormone level in each subject.The Hamilton Anxiety Scale(HAMA)and the Hamilton Depression Scale(HAMD)were used to assess the degree of anxiety and depression.In total,30 subjects,including 15 hypothyroidism and 15 sex-and age-matched normal controls.A resting-state blood oxygen level dependent fMRI were performed using GE Discovery MR750 3.0T magnetic resonance scanner to obtain resting-state images.After data preprocessing,by the in-house script that was written in the Linux platform we got the globle-FCD、short-FCD and long-FCD of each one.Then we use two sample t-test to discover the brain areas with significant differentiation of FCD values.The brain areas which show significant differentiation in short-FCD were defned as regions of interest(ROI).ROI based functional connectivities(FC)were analyzed to explore some possible abnormalities.At last,Pearson correlation analysis was used to investigate the relationships among FCD value of each ROI,the serum thyroid hormone value and the scores of HAMA and HAMD in patients with hypothyroidism.Results:1.Compared with normal controls,patients with hypothyroidism showed globle-FCD significantly increased in the left inferior orbit frontal gyrus,left middle orbital frontal gyrus,and left inferior triangle frontal gyrus(P < 0.001,AlphaSim corrected).2.Compared with normal controls,patients with hypothyroidism showed short-FCD significantly decreased in the left middle frontal gyrus,left inferior orbital frontal gyrus,and left middle orbital frontal gyru(P<0.001,AlphaSim corrected).3.Compared with normal controls,patients with hypothyroidism showed long-FCD significantly increased in the left middle frontal gyrus(P<0.001,AlphaSim corrected).4.In contrast with controls,hypothyroid patients showed stronger FC between the left middle frontal gyrus and left inferior triangle frontal gyrus,left superior temporal gyrus temporal pole,left insula,left cingulate gyrus and bilateral supplementary motor area(P<0.001,AlphaSim corrected).5.Pearson correlation analysis: no significant differentiation between two groups was found(P>0.05).Conclusions:1.The decreased thyroid hormone may cause abnormal local brain function in the left inferior orbit frontal gyrus,left middle orbital frontal gyrus,and left inferior triangle frontal gyrus,short-FCD of this brain area decreased,and may be associated with the neuropsychiatric symptoms in patients with hypothyroidism,such as emotional disorders.2.The decreased thyroid hormone may cause abnormal brain function in the left middle frontal gyrus,long-FCD of this brain area increased,and the brain regions may play a compensatory mechanism for cognitive and emotional dysfunction in patients with hypothyroidism.3.The decreased thyroid hormone may cause abnormal brain function in the left inferior orbit frontal gyrus,left middle orbital frontal gyrus,and left inferior triangle frontal gyrus,the globle-FCD of this brain area decreased,and may be because compensatory mechanism caused by long-FCD plays a more important role.4.Compared with the normal group,hypothyroid patients showed stronger FC between the left middle frontal gyrus and both DMN and bilateral supplementary motor area,and may be associated with motor function deficit need more links to control action.