A Resting-state Functional MRI Study Of Type 2 Diabetes Mellitus

Part Ⅰ Abnormal fractional amplitude of low-frequency fluctuation in type 2 diabetes mellitus: a resting-state f MRI study Objective To explore the changes of spontaneous brain activity in patients with type 2diabetes mellitus(T2DM)by using fractional amplitude of low-frequency fluctuation(f ALFF),which would assist to elucidate the neuropathophysiological mechanism of cognitive dysfunction and comorbid depression in T2 DM patients.Materials and Methods Fifty-six T2 DM patients and 48 age-,sex-,and education-matched healthy controls(HC)underwent neuropsychological test and resting-state functional magnetic resonance imaging(rs-f MRI)scanning,the clinical data were collected.The whole brain f ALFF was calculated and two-sample t-tests were employed to detect significant differences of f ALFF,a seed-based functional connectivity(FC)analysis within the whole brain was conducted,for which the brain areas with significant differences for f ALFF was chosen as the seed region.Additionally,correlation analysis was performed between the f ALFF/FC values and neuropsychological test/clinical variables in T2 DM patients.Results Compared with the HC subjects,T2 DM patients presented lower scores in Montreal Cognitive Assessment(r =﹣5.126,P < 0.001),Clock Drawing Test(r =﹣2.360,P = 0.019)and higher scores in Hamilton Depression Rating Scale-24(r = 5.404,P < 0.001),Beck Depression Inventory(r =1.990,P = 0.049).Importantly,the f ALFF was significantly decreased in the right precuneus and the FC was increased between the right precuneus and the right middle temporal gyrus(MTG)in T2 DM group(Gaussian Random Field correction,voxel-P < 0.005,cluster-P < 0.05).Additionally,positive correlation between the f ALFF value in the right precuneus and thyroid stimulating hormone levels(r = 0.332,P = 0.014)was found in T2 DM group.Conclusions Cognitive impairment and depression symptoms were existed in patients with T2 DM.Decreased spontaneous brain activity in the right precuneus and abnormal FC between the precuneus and the right MTG were also observed,which might be potential neuroimaging biomarkers for the cerebral impairment in T2 DM.Part Ⅱ Alteration of functional connectivity strength in type 2 diabetes mellitus: a resting-state functional MRI study Objective To explore the characteristics of the functional connectivity strength(FCS)of the whole brain existed in T2 DM patients,and its relationship with T2 DM cognitive dysfunction and comorbid depression.Materials and Methods T2 DM patients(n = 56)and age-,sex-,education-matched HC subjects(n = 48)underwent neuropsychological test and rs-f MRI scanning,the clinical data were collected.Then,the whole-brain FC analysis was carried out and the resting-state FCS for a given voxel was calculated as the sum of the connectivities between the voxel and all other voxels.The clusters with significant differences for FCS were defined as the seeds for further seed-based FC analysis.Additionally,correlation analysis was performed between the FCS/FC values and neuropsychological test/clinical variables in T2 DM patients.Results Compared with the HC subjects,T2 DM patients presented lower scores in Montreal Cognitive Assessment(r =﹣5.126,P < 0.001),Clock Drawing Test(r =﹣2.360,P = 0.019)and higher scores in Hamilton Depression Rating Scale-24(r = 5.404,P < 0.001),Beck Depression Inventory(r =1.990,P = 0.049).Importantly,T2 DM patients exhibited stronger FCS in the right middle temporal gyrus(MTG),weaker FC between the right MTG and the left anterior cingulate gyrus(ACC)(Gaussian Random Field correction,voxel-P < 0.001,cluster-P < 0.05).Additionally,Pearson correlation analysis shows the FC between the right MTG and the left ACC was negatively correlated with the score of Hamilton Depression Rating Scale-24 version(r =﹣0.395,P = 0.003),Glycosylated haemoglobin A1 c levels(r =﹣0.303,P = 0.023),and positively correlated with thyroid stimulating hormone levels(r = 0.324,P = 0.017).Conclusions T2 DM patients showed stronger FCS in right MTG and disrupted FC between the right MTG-left ACC,which may participate in brain damage in T2 DM patients and lead to cognitive impairment and depression.