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Mild cognitive impairment has similar alterations as Alzheimer's disease in gut microbiota
Li B, He Y, Ma J, Huang P, Du J, Cao L, Wang Y, Xiao Q et al.. Alzheimer's & dementia : the journal of the Alzheimer's Association, 2019-08-18
Topic: Amyloid, tau and blood-test diagnosis
Objective Gut microbiota changes before the onset of Alzheimer's disease (AD) and the alterations could be detected in the stage of mild cognitive impairment (MCI). The findings might offer diagnostic biomarkers before the onset of dementia. Background AD is the most common cause of dementia, and MCI is the predementia state. Recent studies suggest the alterations in the gut microbial communities associated with AD, whereas the microbiota in MCI before the onset of dementia has not been discovered and characterized in humans. New/updated hypothesis We hypothesize that the dysbiosis happens in the MCI stage. Patients with AD and MCI have decreased microbial diversity, and changes in gut microbiota could be detected for early detection of AD. In our preliminary study, we identified differences between AD and normal controls in 11 genera from the feces and 11 genera from the blood. No difference in genera between AD and MCI was detected. Using the diagnostic model from fecal samples with all different genera input, 93% (28 in 30) of patients with MCI could be identified correctly. Major challenges for the hypothesis The diagnosis of MCI and AD in the study was based on symptoms and neuroimaging, and AD biomarkers should be included for precise diagnosis in further validating studies. Besides, as the microbiota changes longitudinally, their relationship with the progress of dementia needs to be studied in the prospective studies. Linkage to other major theories Escherichia was observed increased at genus level in both fecal and blood samples from AD and MCI. For AD biomarker, postmortem brain tissue from patients with AD showed lipopolysaccharides and gram-negative Escherichia coli fragments colocalize with amyloid plaque. In this way, the amyloid pathogenesis for AD would be triggered during MCI by gut microbiota shifting. Besides, systemic inflammatory reactions caused by compounds secreted by bacteria may impair the blood-brain barrier and promote neuroinflammation and/or neurodegeneration. Furthermore, abnormal metabolites caused by microbial gene functions have an impact on neurodegeneration.
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APA 7th
Li, B., He, Y., Ma, J., Huang, P., Du, J., Cao, L., et al. (2019). Mild cognitive impairment has similar alterations as Alzheimer's disease in gut microbiota. Alzheimer's & dementia : the journal of the Alzheimer's Association. https://doi.org/10.1016/j.jalz.2019.07.002
Vancouver
Li B, He Y, Ma J, Huang P, Du J, Cao L, et al. Mild cognitive impairment has similar alterations as Alzheimer's disease in gut microbiota. Alzheimer's & dementia : the journal of the Alzheimer's Association. 2019. doi:10.1016/j.jalz.2019.07.002. PMID: 31434623.
BibTeX
@article{li2019-31434623,
author = {Li, B. and He, Y. and Ma, J. and Huang, P. and Du, J. and Cao, L. and Wang, Y. and Xiao, Q. and others},
title = {{Mild cognitive impairment has similar alterations as Alzheimer's disease in gut microbiota}},
journal = {Alzheimer's \& dementia : the journal of the Alzheimer's Association},
year = {2019},
doi = {10.1016/j.jalz.2019.07.002},
pmid = {31434623},
url = {https://doi.org/10.1016/j.jalz.2019.07.002}
}
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Key findings
- Recent studies suggest the alterations in the gut microbial communities associated with AD, whereas the microbiota in MCI before the onset of dementia has not been discovered and characterized in humans.
Why it matters
This early study found that people with mild cognitive impairment and people with Alzheimer's disease had similar changes in gut bacteria, and a model using fecal samples correctly identified 93% of the MCI patients. The authors note that diagnosis was based only on symptoms and neuroimaging, so further studies with Alzheimer's biomarkers are needed before this could be used to detect the disease early.
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Study details
- Evidence strengthLow
How this study scored 51/100
Published in a leading specialty journal. Scored zero for study design, sample size, effect reported, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 9 / 10 | Tier 2 — leading specialty journal (Alzheimer's & dementia : the journal of the Alzheimer's Association) |
| Journal's citation record | 2 / 4 | Alzheimer s & Dementia: journal h-index 228 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 2 / 5 | 2019 — within 10 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 6 / 7 | Cited 480 times (OpenAlex, 2026-10-10) |
| Citations per year | 5 / 5 | 53.3 citations a year over 9 year(s) since 2019 |
| Impact for its field and year | 4 / 6 | Cited 13.5× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 2 / 6 | Cited by 8 other studies in this library |
| Still being cited | 4 / 4 | Cited 215 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Shengdi Chen: h-index 47 (OpenAlex, whole career) |
| Institution's track record | 1 / 3 | Shanghai Jiao Tong University: institution h-index 975 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 2 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 31434623) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 51 / 100 | — |
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