Resting-state FMRI Based Analysis Of Mild Cognitive Impairment And The Depression-subgroup

Part I: Amplitude of brain spontaneous functional activity and the Frequency-Dependent changes in patients with mild cognitive impairmentObjective:To compare the brain intrinsic activity differences between mild cognitive impairment(MCI)patients and normal controls(NC),and explore the correlation between brain function changes and memory deficits.Method:Forty-seven NC(male/female: 17/30,average age: 64.91±9.03)and 70 MCI(male/female:36/34,average age: 66.47± 8.01)patients were recruited.Analyses based on 4 rsf MRI measurements of low-frequency fluctuation,including fractional amplitude of lowfrequency fluctuation(f ALFF),percent amplitude of fluctuation(Per AF,here we calculated both m Per AF and Per AF)and Wavelet-ALFF,within full frequency(0.01–0.1Hz),Slow-4(0.027–0.073 Hz)and Slow-5(0.01–0.027 Hz)separately.Results:Through f ALFF analysis,we found that results in the Norm-1 frequency band and the Slow-4 frequency band are roughly the same,that is,the frontal lobe,occipital lobe,and cerebellum are increased in MCI,while the temporal lobe and parahippocampal gyrus were decreased;while in the Slow-5 frequency band,only cetebellum was found increased,and the putamen f ALFF was found decreased.The Wavelet-ALFF analysis showed that in the main frequency band,inferior temporal gyrus(IFG)increased while cerebellum decreased in MCI;in the Slow-4 band,in addition to the increase in inferior temporal gyrus(ITG),we also found that the Wavelet-ALFF in prefrontal lobe increased in MCI,which suggests that the frontal lobe is frequency-dependent.In the Slow-5frequency band,we did not find significant differences between groups.In m Per AF,it was observed that in the main frequency band,the frontal lobe,and the lateral periventricular showed increase in MCI;while in the Slow-4 sub-band,the m Per AF was decreased in the fusiform gyrus.In the main frequency band,MCI has lower Per AF values in ITG and cerebellar than NC,Per AF.In the Slow-4 frequency band,in addition to the ITG and cerebellum,the Per AF value also decreased in the parahippocampal gyrus,precuneus,and parietal lobe in MCI.In the Slow-5 band,it is only reduced in the cerebellum.Further,we found that in the Norm-1 band,the Per AF value in cerebellum and ITG of MCI patients has a negative correlation with cognitive scores.In the Norm-1band,the Per AF value in parahippocampal gyrus were found a negative correlation with cognitive scores.Conclusions:Our study found that MCI has spontaneous changes in brain function in the default network and Salience Network through various LFF measurements,and further identified frequency-dependency in m Per AF and Per AF.The changes of LFF could be used as an early diagnositic biomarker for found MCI.The brain functional activity changes reveal a negative moderating effect on cognitive functions.PartⅡ: Amplitude of brain spontaneous functional activity and the Frequency-Dependent changes in MCI patients with or without depressionObjective:To compare the brain intrinsic activity differences between mild cognitive impairment with depression(MCID)and MCI without depression(MCIND),and to assess the correlation between brain function changes and memory deficits.Method:A total of 76 MCI patients were recruited in this study,including 30 MCID patients(male/female,16/14,age: 67.37±10.19)and 46 MCIND patients(male/female,25/21,age:67.65±7.65).Analyses based on 4 rsf MRI measurements of low-frequency fluctuation,including fractional amplitude of low-frequency fluctuation(f ALFF),percent amplitude of fluctuation(Per AF,here we calculated 2 sub-types of Per AF)and Wavelet-ALFF,within full frequency(0.01–0.1 Hz),Slow-4(0.027–0.073 Hz)and Slow-5(0.01–0.027Hz)separately.Results:In terms of brain spontaneous function activity,MCID patients showed changes in brain spontaneous activity compared with MCIND patients.The MCID groups showed lower Wavelet-ALFF value in the frontal lobe and cingulate gyrus the MCIND group,which had no obvious frequency band specificity.In Per AF,the MCID group is higher than MCIND in all three frequency bands.In the main frequency band and the Slow-4frequency band,MCID has higher Per AF values in the frontal and parietal lobe than MCIND.In the Slow-5 frequency band,in addition to the above-mentioned brain regions,the Per AF value in the precuneus is also found increased.Conclusion:Our study found that compared with MCIND,MCID has spontaneous function changes in brain function in frontal lobe,cingulate gyrus,precuneus and parahippocampal gyrus.The frequency-dependency in precuneus and para hippocampal gyrus were found in the Slow-4 and Slow-5 bands.It suggests that the influence of depressive symptoms on MCI patients may be related to the changes in DMN function.Compared with f ALFF,Per AF and Wavelet-ALFF might be more sensitive to identify MCID and MCIND.Part Ⅲ: Amplitude of brain spontaneous functional activity and the Frequency-Dependent changes in MCI patients with or without depressionObjective:The purpose is to compare the brain function connectivity and the whole brain network connectivity differences between mild cognitive impairment and normal controls,and mild cognitive impairment with depression(MCID)and MCI without depression(MCIND).Method:We compared the function connectivity(FC)between the default mode network(DMN)and the whole brain between MCI and NC,and then compered the FC mode differences between MCID and MCIND.Furthermore,we compared the whole brain degree centrality(DC)between the groups.We also estimated whether these changes have a frequency-dependency.Results:We found that the FC of MCI increased in middle frontal gyrus the middle temporal gyrus compared with NC in the Norm-1 and Slow-4 frequency bands;while the FC decreased in cuneus and lingual gyrus in Norm-1 and Slow-5.As for DC,DC reduced in the parahippocampus gyrus and inferior frontal gyrus in Norm-1 and Slow-4,while in Slow-5,only the cerebellum DC was reduced.In MCID,compared with MCIND,FC increased in middle temporal gyrus in Norm-1 and Slow-5,while in inferior temporal gyrus,middle occipital gyrus,precentral gyrus and cuneus decreased.Moreover,the FC also increased in the inferior parietal gyrus in Slow-4.The DC in middle frontal gyrus,middle temporal gyrus and limbic system of MCID enhanced compares with MCIND in Norm-1;DC increased in the occipital lobe and decreased in the frontal lobe in Slow-4.In the Slow-5frequency band,only the DC of the frontal lobe increases.Conclusion:Our study found that the local FC and global DC changed in both MCI and MCID subgroup.These changes might further interprete the phathogenesis of MCI.FC and DC might be helpful for MCI diagnosis.