Altered Gut Microbiota and Its Clinical Relevance in Mild Cognitive Impairment and Alzheimer’s Disease: Shanghai Aging Study and Shanghai Memory Study
Authors: Zheng Zhu, Xiaoxi Ma, Jie Wu, Zhenxu Xiao, Wanqing Wu, Saineng Ding, Li Zheng, Xiaoniu Liang, Jianfeng Luo, Ding Ding, Qianhua Zhao
Full Research Paper: https://pubmed.ncbi.nlm.nih.gov/36235612/
Research Paper Summary:
The research paper “Altered Gut Microbiota and Its Clinical Relevance in Mild Cognitive Impairment and Alzheimer’s Disease: Shanghai Aging Study and Shanghai Memory Study” investigates the relationship between gut microbiota and cognitive impairment, including mild cognitive impairment (MCI) and Alzheimer’s disease (AD). The study analyzed fecal samples from 128 participants, including healthy individuals, those with MCI, and those with AD, and found that the gut microbiota composition of individuals with cognitive impairment was significantly different from that of healthy individuals. Specifically, the study found that individuals with cognitive impairment had lower levels of beneficial bacteria, such as Bifidobacterium, and higher levels of harmful bacteria, such as Escherichia coli.
The overall structure of the gut microbiota based on the analysis of microbial diversity among NC, MCI, and AD. (A) Venn diagram showing the overlap of the OTUs found in the gut microbiota among NC, MCI, and AD. (B) The gut microbial compositions at the phylum levels among NC, MCI, and AD. NC, cognitively normal controls; MCI, mild cognitive impairment; AD, Alzheimer’s disease; OTUs, operational taxonomic units.
Beta diversity analysis in NC, MCI, and AD. (A–C) The beta diversity of NC, MCI, and AD by bray–Curtis (A), unweighted unifrac (B), and weighted unifrac (C) analyses. (D) Non-metric multidimensional scaling (NMDS) analysis of the gut microbial in NC, MCI, and AD. (E) Principal component analysis (PCA) among the three groups. (F) Principal co-ordinates analysis (PCoA) among the three groups. NC, cognitively normal controls; MCI, mild cognitive impairment; AD, Alzheimer’s disease; Nmds, non-metric multidimensional scaling; PCA, principal component analysis; PCoA, principal co-ordinates analysis.
Bacterial taxa with different abundances among NC, MCI, and AD. (A) The differences of the LDA scores, histogram for bacterial genera between NC and MCI. (B) The differences of the LDA scores, histogram for bacterial genera between NC and AD. (C) The differences of the LDA scores, histogram for bacterial genera between MCI and AD. (D) Venn diagram of the genera showing the differences among the three groups. NC, cognitively normal controls; MCI, mild cognitive impairment; AD, Alzheimer’s disease; LDA, linear discriminant analysis.
Correlations between the five specific taxa and clinical characteristics. The correlation coefficients (Corr) are displayed. Red or blue signified positive or negative correlation, respectively. MMSE, Mini-mental State Examination; MoCA, Montreal Cognitive Assessment; ADL, Activities of Daily Living; CDR, Clinical Dementia Rating; The composite Z scores were computed for specific cognitive domains including memory, attention, visuospatial ability, language, and executive function. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.
The abundance of the five specific taxa among different clinical subgroups. (A) Comparison of the abundance of five taxa Erysipelatoclostridiaceae, Erysipelotrichales, Saccharimonadales, Patescibacteria, and Saccharimonadia in NC, MCI, and AD. (B) Comparison of the abundance of five taxa Erysipelatoclostridiaceae, Erysipelotrichales, Saccharimonadales, Patescibacteria, and Saccharimonadia in CDR 0, 0.5, 1, 2, and 3 subgroups; (C) Comparison of the abundance of five taxa Erysipelatoclostridiaceae, Erysipelotrichales, Saccharimonadales, Patescibacteria, and Saccharimonadia in APOE 4 positive (APOE+) or negative (APOE−) subgroups. NC, cognitively normal controls; MCI, mild cognitive impairment; AD, Alzheimer’s disease; CDR, Clinical Dementia Rating; APOE, apolipoprotein E; OTUs, operational taxonomic units. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001.
The study also found a correlation between gut microbiota composition and cognitive performance, with individuals with MCI and AD showing poorer cognitive performance and lower levels of beneficial bacteria. These findings suggest that the gut microbiota may play a role in the development and progression of cognitive impairment, and that maintaining a healthy gut microbiota may have clinical implications for preventing or treating cognitive decline.
Overall, the study highlights the potential importance of the gut-brain axis in cognitive health, and suggests that future research should explore the mechanisms underlying this relationship and the potential for interventions to improve gut microbiota composition in individuals with cognitive impairment.
