Cognitive decline associated with Parkinson disease (PD) is common and highly disabling. 4 key findings →
Design: cohort study Participants: 45 Evidence: moderate
Full summary, score breakdown and related studies → Original source Free full text
Research
27,780 Alzheimer's and dementia studies in plain English, each scored out of 100.
Except for αSyn, the additional biomarkers did not differentiate PD and HC, and none showed longitudinal differences, but most markers predict cognitive decline in PD during follow-up. 3 key findings →
Design: longitudinal study Evidence: moderate
Full summary, score breakdown and related studies → Original source Free full text
Here, we investigated if TAR-DNA-binding protein-43 (TDP-43), the disease protein in frontotemporal lobar degeneration and ubiquitin inclusions with or without motor neuron disease as well as amyotrophic lateral sclerosis, also formed inclusions in Lewy body (LB) disorders including Parkinson's disease (PD) without or with dementia (PDD), and dementia with LBs (DLB) alone or in association with Alzheimer's disease (AD). 3 key findings →
Evidence: low
Full summary, score breakdown and related studies → Original source Full text may need a subscription
18 F-flortaucipir uptake was elevated in PSP versus controls and PD patients in a pattern consistent with the expected distribution of tau pathology. 3 key findings →
Participants: 33 Evidence: low
Full summary, score breakdown and related studies → Original source Free full text
This study compared individuals whose clinical diagnosis of Alzheimer's disease (AD) matched or did not match neuropathologic results at autopsy on clinical and functional outcomes (cognitive impairment, functional status and neuropsychiatric symptoms). 4 key findings →
Design: longitudinal study Evidence: moderate
Full summary, score breakdown and related studies → Original source Free full text
A higher proportion of patients in the immediate feedback arm showed a change in diagnosis compared to the controls (32.6 vs. 6.4%; p = 0.0001). 3 key findings →
Participants: 618 Evidence: high
Full summary, score breakdown and related studies → Original source Free full text
Plasma NfL is a useful prognostic biomarker for PD, predicting clinical conversion to mild cognitive impairment or dementia. © 2021 International Parkinson and Movement Disorder Society. 1 key finding →
Design: cross-sectional Evidence: moderate
Full summary, score breakdown and related studies → Original source
Baseline data of 423 PD patients and 196 HCs yielded no between-group differences in demographic characteristics. 3 key findings →
Evidence: moderate
Full summary, score breakdown and related studies → Original source Free full text
Florbetapir F18 has been approved by the Food and Drug Administration for in vivo assessment of amyloid pathology in patients undergoing evaluation for Alzheimer disease (AD). 3 key findings →
Participants: 229 Evidence: low
Full summary, score breakdown and related studies → Original source Full text may need a subscription
Patients with Parkinson's disease (PD) often have cognitive deficits from the time of diagnosis. 4 key findings →
Evidence: moderate
Full summary, score breakdown and related studies → Original source Free full text
Few studies have examined connected speech in demented and non-demented patients with Parkinson's disease (PD). 2 key findings →
Participants: 35 Evidence: low
Full summary, score breakdown and related studies → Original source Free full text
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 27,780 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 27,780 records, built mostly from automated pulls of Europe PMC (61.1% of the library) and OpenAlex (18.3%), 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.
1,034 records (3.7% of the library) are not peer-reviewed — 962 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 →