| Purpose:By detecting the gut microbiot and metabolites in patients with Alzheimer’s disease（AD）and performing correlation analysis with PET-CT,explore the changes in the gut microbiota and its metabolites in patients with AD,search for potential biomarkers for the diagnosis of AD,explore the underlying mechanisms by which changes in intestinal microecology affect AD,and provide an updated evidence-based basis for the diagnosis of AD.Materials and Methods:A total of 20 subjects were included.The patient group included 10 patients who were diagnosed as Alzheimer’s disease for the first time in China-Japan Union Hospital of Jilin University from January 2020 to November 2020,and 10 patients without cognitive impairment-related diseases during the same period were included as normal control group（NC group）.General clinical data were collected from all subjects,and cognitive function was assessed using the Mini-Mental State Examination（MMSE）,Montreal Cognitive Assessment（MoCA）,Clinical Dementia Rating scale（CDR）,and Auditory Word Learning Test（AVLT）.Collect blood and stool samples from all subjects,detect the types and abundance of gut microbiota by 16S r RNA high-throughput sequencing technique,analyze the diversity of gut microbiota composition,and detect the types and contents of gut microbiota metabolites in blood samples by metabonomics.18F-FDG and 11C-PIB examinations were performed in 10 AD subjects.Neuro Q quantitative analysis was performed on FDG-PET results,and standard uptake ratio analysis was performed on PIB-PET results.Significant differences in microbiota and metabolites were correlated with PET-CT and plotted as heatmaps.Results:The types and abundances of gut microbiota in AD group and NC group were different.Compared with the NC group,the relative abundance of Firmicutes,Proteobacteria and Actinobacteria decreased in the AD group,while the relative abundance of Bacteroidetes increased significantly.Among them,Acidaminococcaceae,Desulfovibrio,Rubritalea,Tyzzerella 3 and Butyricicoccus have significant differences between the NC group and the AD group.Thioetheramide-PC,D-mannose,2-oxoadipic acid,Bilirubin,Dihydro-4,4-Dimethyl-2,3-furandione（3-carboxypropyl）Trimethylammonium cation and L-valine were significantly different metabolites in the two groups.The differential microbiota and metabolites were significantly correlated with the cognitive function scale scores,as well as with the specific brain regions with decreased metabolism of FDG-PET and the brain regions with increased SUVR value of PIB-PET.Conclusion:1.Patients with AD have obvious changes in gut microbiota,which may be an important factor in the pathogenesis of AD.2.Changes in gut microbiota and metabolites in patients with AD can be a potential biomarker for the diagnosis of AD.3.The significantly different microbiota and metabolites in the AD group were correlated with decreased glucose metabolism and amyloid deposition in specific brain regions. |
