The gut microbiota has been linked to various neurological disorders via the gut-brain axis. 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Research
30,180 Alzheimer's and dementia studies in plain English, each scored out of 100.
Dementia is a comprehensive category of brain diseases that is great enough to affect a person's daily functioning. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
Neurological diseases, such as Parkinson's disease, Alzheimer's disease, amyotrophic lateral sclerosis (ALS) and multiple sclerosis, are often associated with functional gastrointestinal disorders. 2 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The gut-brain axis is a bidirectional communication network functionally linking the gut and the central nervous system (CNS). 2 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The aggregation of amyloid-β peptide (Aβ) has been linked to the formation of neuritic plaques, which are pathological hallmarks of Alzheimer's disease (AD). 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The gut and brain form the gut-brain axis through bidirectional nervous, endocrine, and immune communications. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
The brains of 46 control subjects and 21 Alzheimer's disease (AD) patients were studied to determine whether there are age-related or AD-related changes in the vasoactive intestinal polypeptide (VIP) neuron population of the human suprachiasmatic nucleus (SCN). 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
Metabolic endotoxemia is a condition in which blood lipopolysaccharide (LPS) levels are elevated, regardless of the presence of obvious infection. 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
41/100
Increasing evidence suggests that gut dysbiosis plays vital roles in a variety of gut-brain disorders, such as Alzheimer's disease (AD). 4 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Apolipoprotein E ( APOE ) genotype is the strongest prevalent genetic risk factor for Alzheimer's disease (AD). 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The kynurenine pathway is important in cellular energy generation and limiting cellular ageing as it degrades about 90% of dietary tryptophan into the essential co-factor NAD + (nicotinamide adenine dinucleotide). 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Psychobiotics are a group of probiotics that affect the central nervous system (CNS) related functions and behaviors mediated by the gut-brain-axis (GBA) via immune, humoral, neural, and metabolic pathways to improve not only the gastrointestinal (GI) function but also the antidepressant and anxiolytic capacity. 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The gut-brain axis is bidirectional, and gut microbiota influence brain disorders including Alzheimer's disease (AD). 2 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Gut microbiota influences the central nervous system disorders such as Alzheimer's disease (AD). 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The bidirectional communication between the central nervous system (CNS) and the gut microbiota plays a pivotal role in human health. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
The gut-brain axis is increasingly recognized as an important pathway of communication and of physiological regulation, and gut microbiota seems to play a significant role in this mutual relationship. 2 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Gut microbiota (GM) can influence various neurological outcomes, like cognition, learning, and memory. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
Mucus is integral to gut health and its properties may be affected in neurological disease. 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Gut microbiome is a community of microorganisms in the gastrointestinal tract. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
Misfolded protein aggregates represent a continuum with overlapping features in neurodegenerative diseases, but differences in protein components and affected brain regions. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
Adequate supply of blood and structural and functional integrity of blood vessels are key to normal brain functioning. 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Increasing evidence recognizes Alzheimer's disease (AD) as a multifactorial and heterogeneous disease with multiple contributors to its pathophysiology, including vascular dysfunction. 2 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by the pathological accumulation of amyloid beta (Aβ) peptides and neurofibrillary tangles containing hyperphosphorylated neuronal tau protein. 1 key finding →
Evidence: low
Full summary, score breakdown and related studies → Original source
The blood vessels vascularizing the central nervous system exhibit a series of distinct properties that tightly control the movement of ions, molecules, and cells between the blood and the parenchyma. 4 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
The CNS is protected by the immune system, including cells that reside directly within the CNS and help to ensure proper neural function, as well as cells that traffic into the CNS with disease. 5 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source
Where “Free full text” comes from
Free full text links and the Full text may need a subscription label come from Unpaywall, Europe PMC and OpenAlex records of free copies, checked 10 Oct 2026. A study with neither is unknown, not paywalled. Show only studies that are free to read
How the 0–100 score works — and why some entries are capped
This is alzhub's own score. It is not an official metric, not an impact factor, and no journal, publisher or ranking body endorses it. We built it so that a reader who is not a scientist can tell a landmark trial from a conference abstract without having to already know the difference. Every point comes from one of 20 components, all of them printed on the study itself, so you can disagree with our arithmetic rather than having to trust the total.
- Journal tier up to 10 pts
- Journal's citation record up to 4 pts
- Study design up to 12 pts
- Strength of evidence up to 5 pts
- Peer-review validation up to 10 pts
- How recent up to 5 pts
- Sample size up to 4 pts
- Effect reported up to 3 pts
- Studied in people up to 3 pts
- Randomised / blinded up to 2 pts
- Times cited up to 7 pts
- Citations per year up to 5 pts
- Impact for its field and year up to 6 pts
- Cited by studies here up to 6 pts
- Still being cited up to 4 pts
- Senior author's track record up to 4 pts
- Institution's track record up to 3 pts
- Multi-centre collaboration up to 3 pts
- Indexed in PubMed up to 2 pts
- Free to read up to 2 pts
Journals are placed in ordered tiers, never given a numeric impact factor — we could not verify current impact factors from a source we control, and an invented one would be worse than none. Tier 1 is the top-tier general journals (NEJM, The Lancet, JAMA, Nature, Science, Nature Medicine); tier 2 is the leading specialty journals; tier 3 is every other peer-reviewed journal. A separate part scores how much the journal's own papers are cited, which tells the tier-3 journals apart.
Two rules we don't bend. First, we never fill in a missing value: if a record does not state a sample size or a design, that component scores zero, and if we simply have no data for a part, such as a citation count, that part is left out and the study is scored on the parts we could check. The study card says which. Second, anything that is not a peer-reviewed article is capped at 16/100 and carries a warning chip — so a conference abstract or a company press release can never outrank a peer-reviewed paper, no matter how good it looks.
We rank a rigorous null result — a good trial showing that something does not work — above an early positive finding. Someone deciding whether to buy a supplement is served by that, and the rigour is already counted by the design and journal components.
The score is computed from the published data alone and is reproducible: the same file always yields the same numbers.
See the whole rubric drawn out → — four charts covering all 30,180 studies: how the scores are spread and where the cap bites, which of the 20 components the library is strong and weak on, which subjects rest on stronger evidence, and what kinds of study each subject is actually built from.
What this library is — and isn't
This is a large sample of the Alzheimer's literature, not an exhaustive index of it. It holds 30,180 records, built mostly from automated pulls of Europe PMC (64.2% of the library) and OpenAlex (16.9%), plus smaller pulls from PubMed, Crossref and medRxiv. If a study, a drug, or a finding isn't here, that is not evidence it doesn't exist in the literature — it may simply not have been pulled in yet.
1,037 records (3.4% of the library) are not peer-reviewed — 964 of those are preprints posted before any journal review, and the rest are conference abstracts, regulatory notices and reports. Every study card on this page states its status plainly, and the score above is capped for anything that isn't a peer-reviewed article.
See the full, machine-readable breakdown of this library's coverage →