Home › Research › Disease mechanisms
Gut microbiota in patients with Alzheimer's disease spectrum: a systematic review and meta-analysis
Hung CC, Chang CC, Huang CW, Nouchi R, Cheng CH.. Aging, 2022-01-14
Topic: Gut, metabolism and diet
Context Gut dysbiosis has been proposed as one of pathologies in patients with Alzheimer's disease (AD) spectrum. Despite such enthusiasm, the relevant results remain substantially controversial. Objective A systematic review and meta-analysis were performed to investigate the differences of gut microbiota (GM) between patients with AD spectrum (including mild cognitive impairment [MCI] and AD) and healthy controls (HC). Data sources PubMed, MEDLINE, Scopus, and Cochrane Library from January 2000 to August 2021. Eligibility criteria for study selection: Observational trials and pre-intervention data of intervention trials that investigated the abundance of GM in patients with AD spectrum and HC. Data extraction and synthesis Two reviewers independently identified articles, extracted data, and evaluated the risk of bias. The effect sizes were performed by a random-effect, inverse-variance weighted model. The effects of different countries and of clinical stages on GM abundance were also examined. Results 11 studies consisting of 378 HC and 427 patients with AD spectrum were included in the meta-analysis. Patients with AD, but not MCI, showed significantly reduced GM diversity as compared to HC. We also found more abundance of Proteobacteria , Bifidobacterium and Phascolarctobacterium , but less abundance of Firmicutes , Clostridiaceae , Lachnospiraceae and Rikenellaceae in patients with AD spectrum as compared with HC. The profiles of abundance of Alistipes and Bacteroides in HC and AD spectrum were differentially affected by countries. Finally, when considering clinical stage as a moderator, the comparisons of abundance in Clostridiaceae and Phascolarctobacterium showed large effect sizes, with gradient changes from MCI to AD stage. Limitations The inclusion of studies originating only from China and the U.S. was a possible limitation. Conclusions Patients with AD spectrum demonstrated altered GM abundance, which was differentially mediated by countries and clinical stages.
Key findings
- Despite such enthusiasm, the relevant results remain substantially controversial.
- Results 11 studies consisting of 378 HC and 427 patients with AD spectrum were included in the meta-analysis.
- Patients with AD, but not MCI, showed significantly reduced GM diversity as compared to HC.
- We also found more abundance of Proteobacteria , Bifidobacterium and Phascolarctobacterium , but less abundance of Firmicutes , Clostridiaceae , Lachnospiraceae and Rikenellaceae in patients with AD spectrum as compared with HC.
- Conclusions Patients with AD spectrum demonstrated altered GM abundance, which was differentially mediated by countries and clinical stages.
Study details
- Study designsystematic review
- Participants427
- Evidence strengthHigh
How this study scored 79/100
Published in a peer-reviewed journal, and it is a systematic review of all the studies on the question. Scored zero for effect reported because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 46 of the 58 points we could judge it on, which is 79 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Aging) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 12 / 12 | A systematic review of all the studies on the question |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 3 / 5 | 2022 — within 6 year(s) of the newest study here |
| Sample size | 2 / 4 | 427 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 35027502) |
| Free to read | 2 / 2 | Free to read |
| Points | 46 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 46 of the 58 points we could judge it on is 79 out of 100. |
| Total | 79 / 100 | — |
What each of these 20 components measures, and what this score is not →
Read the original
Free copy unknown: no free-copy check has an answer for this record yet. That does not mean it is paywalled.
Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Hung, C. C., Chang, C. C., Huang, C. W., Nouchi, R., & Cheng, C. H. (2022). Gut microbiota in patients with Alzheimer's disease spectrum: a systematic review and meta-analysis. Aging. https://doi.org/10.18632/aging.203826
Vancouver
Hung CC, Chang CC, Huang CW, Nouchi R, Cheng CH. Gut microbiota in patients with Alzheimer's disease spectrum: a systematic review and meta-analysis. Aging. 2022. doi:10.18632/aging.203826. PMID: 35027502.
BibTeX
@article{hung2022-35027502,
author = {Hung, C. C. and Chang, C. C. and Huang, C. W. and Nouchi, R. and Cheng, C. H.},
title = {{Gut microbiota in patients with Alzheimer's disease spectrum: a systematic review and meta-analysis}},
journal = {Aging},
year = {2022},
doi = {10.18632/aging.203826},
pmid = {35027502},
url = {https://doi.org/10.18632/aging.203826}
}