Correlation Between Abnormal Brain Activity And HPT Axis Imbalance In Bipolar Depressive Disorder Based On Resting-state FMRI

Objective: To explore brain local activity and functional connectivity of bipolar II disorder(BD)by using amplitude of low frequency fluctuations(ALFF)and functional connectivity(FC).Combined with cognitive function,analyzing abnormal brain activity and cognitive function of all patients,provide theoretical basis for the early identification and intervention of BD patients.Materials and methods: Resting-state functional magnetic resonance imaging(rs-f MRI)was performed on 90 unmedicated BD II depressive patients and 100 healthy controls(HCs).The rs-f MRI dataset was preprocessed and the ALFF values during the conventional frequency band(0.01-0.1Hz),slow5 band(0.01-0.027Hz)and slow4 band(0.027-0.073)were calculated respectively.Two sample t test was performed to compare the differences of ALFF values between two groups in conventional frequency.Two-factor repeated measures analysis of variance and post hoc analysis were used to compare the ALFF values of sub-bands of slow5 band and slow4 band between different groups.The brain regions shown significant differences between the groups were defined as masks.To obtain the FC value between the mask and the other brain voxels,the correlation coefficients between the mask and the other brain voxels were calculated.Two sample t test was performed to compare the differences of FC values between two groups.Subsequently,digit span test,Symbol Digital Modalities Test(SDMT),Wisconisin Card Sorting Test-modified(WCST),Trail Making Test(TMT)and the verbal fluency test were used to assess cognitive function of all subjects.Two sample t test or analysis of covariance was performed to compare the cognitive function between two groups.Finally,partial correlation analysis was conducted between the ALFF value,FC value and the clinical information and cognitive function of patients.Results: 1.The results of ALFF analysis showed that when compared with HCs,BD II depressive patients showed decreased ALFF values in the bilateral precuneus of the conventional frequency band and the slow4 band,decreased ALFF values in the right precuneus and increased ALFF values in the right occipital middle gyrus of the slow5 band.2.The results of FC analysis showed that when compared with HCs,BD II depressive patients showed decreased FC between the right precuneus and the bilateral medial prefrontal cortex and bilateral precuneus of the slow5 band,decreased FC between the bilateral precuneus and bilateral precuneus of the slow4 band.3.The results of cognitive function showed that when compared with HCs,BD II depressive patients showed reduced SDMT score,number of categories completed of WCST and verbal fluency score,increased TMT-B Time,number of total errors and number of perseverative errors of WCST.There was no significant correlation between cognitive function and abnormal AFLL and FC values.Conclusion: 1.Local activity and functional connections in important brain regions of the default mode network were destroyed in BD II depressive patients.2.The verbal memory,attention,anti-interference in BD II depressive patients may be impaired.Objective: To explore brain local activity and functional connectivity of BD II depressive patients by using the ALFF and FC approach.Then we collected the hypothalamic-pituitary-thyroid(HPT)axis hormones.Subsequently,analyzing the abnormal brain activity and HPT axis of BD II depressive patients,and the correlation between brain activity and HPT axis was analyzed,to explore the possible biological mechanism of BD II depression of imaging-endocrine levels,and to provide a basis for the diagnosis and treatment of BD.Materials and methods: Rs-f MRI was performed on 90 unmedicated BD II depressive patients and 100 HCs.The process and statistical methods of rs-f MRI dataset were the same as that in chapter 1.When finishing the MRI scans,the subject was determined the iodine thyroid free three original glycine(FT3),three iodine in serum thyroid glycine(TT3),four free iodine thyroid former glycine(FT4),serum total four iodine thyroid original glycine(TT4)and thyroid-stimulating hormone(TSH)concentrations by using direct chemiluminescence method in 24 hours.Two sample t test or analysis of covariance was performed to compare the HPT axis between two groups.Finally,partial correlation analysis was conducted between the ALFF value,FC value and the HPT axis of patients.Results: 1.The results of ALFF and FC comparisons between groups were the same as those in chapter 1.2.The results of HPT axis analysis showed that when compared with HCs,BD II depressive patients showed decreased FT3,TT3 and TSH concentrations and increased FT4 concentrations.3.Correlation analysis showed that:(1)There was a negative correlation between ALFF and FT4 concentration and a positive correlation between ALFF and TSH concentration in the precuneus of conventional frequency band(0.01-0.1Hz)and of slow5 band in the BD II depressive patients.(2)The ALFF in the precuneus of slow4 band was positively correlated with TSH concentration in the BD II depressive patients.(3)The FC between the precuneus and the precuneus of slow4 band was positively correlated with TSH concentration.Conclusion: 1.HPT axis function may weaken in BD II depressive patients.2.The dysfunction of HPT axis in BD II depressive patients may be related to the abnormal spontaneous activity of precuneus.3.Combined with chapter 1,abnormal HPT axis in BD II depressive patients may be involved in the occurrence of abnormal spontaneous brain activity,which leads to the impairment of cognitive function.