The Relationship Between The Difference Of Serum MiRNA Levels Of MCI,AD And VD And Cognitive Impairment And The Exploration Of Improving The Recognition Of These Diseases

Objective:To investigate whether there were differences in the relative expression levels of miRNA-107,miRNA-206 and miRNA-132 in serum of MCI,AD and VD patients;To investigate whether miRNA-107,miRNA-206 and miRNA-132 are correlated with the severity of cognitive impairment in patients;To explore the role of miRNA-107,miRNA-206 and miRNA-132 in the differentiation of normal elderly people,MCI,AD and VD,and whether the combination of two or more miRNAs can improve the recognition of patients in the above groups.Methods:According to the matching principle of age,gender,education level（age±10 years old,gender ratio of male to female is approximately 1:1,education level is both illiterate or primary or junior high school or above）,the groups were grouped by Mini-Mental State Examination（MMSE）,Activities Daily Living（ADL）and Clinical Dementia Rating Scale（CDR）and which were used to evaluate the severity of cognitive impairment.Finally,37cases of MCI group,36 cases of AD group,30 cases of VD group and 37 cases of normal control elderly were screened out.Normal control group and MCI group were recruited from Zhongnan Street Community,Fang Cun,Li Wan District,Guangzhou City,Guangdong Province from August 2020 to December 2020.According to the MCI diagnostic criteria of Petersen et al.[46],combined with MMSE scale assessment（18～21scores for illiteracy,21～24 scores for primary school education,25～27 scores for secondary school education or above）,MCI patients were screened out and all enrolled in the study.The samples of AD and VD patients were all from inpatients in the geriatric department of the Affiliated Brain Hospital of Guangzhou Medical University between2014 and 2020.The diagnosis for AD was based on the National Institute of Neurological Stroke and Speech Disorders and the National Institute on Aging and Alzheimer’s Disease（NINCDS-ADRDA）and the National Institute on Aging and Alzheimer’s Disease（NINCD-ADRDA）Association,NIA-AA)diagnostic criteria;VD meets the American Society for Neurology,Speech Disorders and Stroke-International Society for Neuroscience criteria.The MMSE and CDR of AD and VD patients met the requirements of illiteracy<17 scores,primary school<20 scores,middle school or above<24 scores,CDR≥1 points respectively,and they were enrolled when they were in the hospital.Quantitative polymerase chain reaction（q PCR）method was used to calculate the relative expression levels of miRNA-107,miRNA-206 and miRNA-132 in serum of each group by2^-△△CT method.Statistic Package for Social Science（SPSS 22.0）software was used to analyze the demographic data,the expression levels of serum miRNA-107,miRNA-206and miRNA-132 in different subgroups,and draw their ROC curve.the correlation between serum level of miRNA and cognitive impairment were analyzed.The influencing factors for the MMSE score of each subgroup were analyzed by multiple linear regression.Results:1.The relative expression levels of serum miRNA-107,206 and 132 in each groupThe relative expression levels of serum miRNA-107 in the normal group,MCI group,AD group and VD group were expressed by the median（25%-75%）as follows:0.18（0.05-0.64）,0.03（0.02-0.05）,0.85（0.61-1.25）and 0.99（0.66-1.40）,the differences were statistically significant（F=212.43,P<0.001）.The relative expression of miRNA-107 in patients with dementia（AD,VD）was significantly higher than that in MCI group.The relative expression levels of serum miRNA-206 in normal group,MCI group,AD group and VD group were 0.86（0.34-1.69）,0.06（0.04-0.10）,0.05（0.03-0.09）and0.04（0.02-0.06）respectively,swhich were indicated by the median（25%-75%）.The difference was statistically significant（F=134.76,P<0.001）.The relative expression of miRNA-206 in patients with cognitive impairment（MCI,AD,VD）was significantly decreased.The relative expression level of serum miRNA-132 in normal group,MCI group,AD group and VD group was 0.60（0.08-0.96）,0.15（0.10-0.25）,0.16（0.10-0.24）,0.07（0.05-0.11）,respectively,which were indicated by the median（25%-75%）.The difference was statistically significant（F=91.17,P<0.001）,and the decrease was more obvious in VD group.2.Serum level of miRNA-107,miRNA-206,miRNA-132 and their area under the curve of cognitive declineThe area under the curve（AUC）of the relative expression levels of miRNA-206 and miRNA-132 in serum to distinguish normal from cognitive decline（including MCI group,AD group and VD group）were 0.845 and 0.732,P<0.001,respectively,their 5%confidence intervals（CI）were 0.790--0.901 and 0.659--0.805,respectively.Further,according to the RCO curve,the area under the curve combined the relative expression levels of serum miRNA-206 and miRNA-132 were 0.897（95%CI:0.858 to 0.936）,P<0.001,in which compared the cognitive decline group with the normal group.The AUC of the relative expression level of serum miRNA-107 in differentiating mild cognitive impairment（MCI）from dementia（AD,VD）was 0.987（P<0.001）,95%CI0.977-0.997.The relative expression level of serum miRNA-132 differentiated AD from VD with AUC of 0.787,P<0.001,95%CI:0.723-0.851.3.The correlation of relative expression levels of miRNA-107,miRNA-206and miRNA-132 in serum were correlated with cognitive functionThe correlation of relative expression levels of miRNA-107,miRNA-206 and miRNA-132in serum with the scores of MMSE,ADL and CDR scales were analyzed by Pearson,the serum miRNA-107 was negatively correlated with MMSE score（r=-0.741,P<0.05）.The serum miRNA-206 and miRNA-132 were positively correlated with MMSE score（r=0.485,0.354,P<0.05）.The serum miRNA-107 was negatively correlated with ADL score（r=-0.675,P<0.05）,while serum miRNA-206 and miRNA-132 were not significantly correlated with ADL score（r=0.094,0.063,P>0.05）.There was no significant correlation between serum miRNA-107,miRNA-206,miRNA-132 and CDR（r=0.167,0.224,0.220,P>0.05）.Multiple linear regression model was used to test the correlation between the relative expression levels of miRNA-107,miRNA-206 and miRNA-132 in serum of each subgroup at baseline and MMSE score,the results showed that only the relative expression level of miRNA-206 in serum had a significant linear relationship with MMSE score in MCI group（B=15.079,P<0.05）,suggesting that when the relative expression level of miRNA-206 increased one unit,MMSE score increased about 15 points on average.Conclusions:1.The relative expression level of serum miRNA-107 in AD and VD patients was significantly higher than that in normal control group and MCI group.The relative expression level of miRNA-107 may be helpful to identify MCI and dementia（AD,VD）。2.The expression levels of miRNA-206 and miRNA-132 in MCI,AD and VD serum were significantly decreased compared with those in normal elderly.MiRNA-206 may be valuable for the identification of normal elderly and patients with cognitive impairment.MiRNA-206 may be helpful in assessing the severity of cognitive impairment in MCI.3.The relative expression of serum miRNA-132 in AD patients was significantly higher than that in VD group.The serum miRNA-132 may play a role in identifying impaired cognitive function and differentiating the types of dementia.4.The combination of serum miRNA-206 and serum miRNA-132 may improve the level of recognition of cognitive impairment（MCI,AD,VD）.