Home › Research › Disease mechanisms
Gut community-level analysis reveals an altered balance between Phocaeicola vulgatus and Bacteroides fragilis in Alzheimer’s disease
Huang Z, McGrath PM, Ferdinand DC, McCormick BA, Ward DV, Bucci V, Haran JP.. bioRxiv, 2026-08-13
Topic: Genetics and APOE
Gut microbiome differences in Alzheimer’s disease (AD) are typically cataloged taxon by taxon, yet bacterial competition and cross-feeding make species’ roles dependent on the entire community. We analyzed 274 stool metagenomes from 119 older adults (18 with AD) as communities, retaining 22 recurring across 1,000 runs. Using our AI framework, we identified 15 species differing in abundance in AD, particularly the commensal Phocaeicola vulgatus (Cohen’s d –0.91, 95% CI [-1.23, –0.59]), a finding robust to repeated sampling. It correlated negatively with its sister species, Phocaeicola dorei ( r –0.57), suggesting possible niche competition; this replicated in an independent cohort ( r –0.43). P. vulgatus was depleted in AD and the opportunistic pathogen Bacteroides fragilis enriched, shifting their balance toward B. fragilis ( d –0.70), a modestly reproduced AD-associated pattern ( d –0.24). Our findings suggest that AD-associated gut microbiome variation extends beyond taxon-specific abundance to the balance between specific species within a community matrix.
Key findings
- Our findings suggest that AD-associated gut microbiome variation extends beyond taxon-specific abundance to the balance between specific species within a community matrix.
Study details
- Participants274
- Evidence strengthModerate
How this study scored 16/100
Preprint — not yet peer-reviewed. It scored 32 on the same rubric, but non-peer-reviewed sources are capped at 16, so it shows as 16. Scored zero for study design, effect reported and randomised / blinded because the record does not state it. We have no data on 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 20 of the 62 points we could judge it on, which is 32 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 2 / 10 | Tier 4 — not a peer-reviewed journal (bioRxiv) |
| Journal's citation record | 0 / 4 | Not a journal article, so the journal's record does not count |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 3 / 5 | Rated “moderate” in our summary |
| Peer-review validation | 4 / 10 | Preprint — not yet peer-reviewed. Hosted on a preprint server. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 2 / 4 | 274 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 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| 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 | 1 / 2 | Not in PubMed, but has a DOI |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 20 / 62 | Scored on 12 of 20 parts. We have no data for the rest, so they are left out: 20 of the 62 points we could judge it on is 32 out of 100. |
| Total | 32 / 100 | Capped to 16 because this is not a peer-reviewed article. |
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. The record names 7 authors; APA and Vancouver show the first six, BibTeX and the downloads carry all of them. Check the citation against the original before you use it.
APA 7th
Huang, Z., McGrath, P. M., Ferdinand, D. C., McCormick, B. A., Ward, D. V., Bucci, V., et al. (2026). Gut community-level analysis reveals an altered balance between Phocaeicola vulgatus and Bacteroides fragilis in Alzheimer’s disease. bioRxiv. https://doi.org/10.64898/2026.08.12.743985
Vancouver
Huang Z, McGrath PM, Ferdinand DC, McCormick BA, Ward DV, Bucci V, et al. Gut community-level analysis reveals an altered balance between Phocaeicola vulgatus and Bacteroides fragilis in Alzheimer’s disease. bioRxiv. 2026. doi:10.64898/2026.08.12.743985.
BibTeX
@article{huang2026-e93b8a8b,
author = {Huang, Z. and McGrath, P. M. and Ferdinand, D. C. and McCormick, B. A. and Ward, D. V. and Bucci, V. and Haran, J. P.},
title = {{Gut community-level analysis reveals an altered balance between Phocaeicola vulgatus and Bacteroides fragilis in Alzheimer’s disease}},
journal = {bioRxiv},
year = {2026},
doi = {10.64898/2026.08.12.743985},
url = {https://doi.org/10.64898/2026.08.12.743985}
}