Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 3 complete abstracts (452 words), 9 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
A degenerative disease of the brain characterized by the insidious onset of dementia. Impairment of memory, judgment, attention span, and problem solving skills are followed by severe apraxias and a global loss of cognitive abilities. The condition primarily occurs after age 60, and is marked pathologically by severe cortical atrophy and the triad of senile plaques; neurofibrillary tangles; and neuropil threads. (From Adams et al., Principles of Neurology, 6th ed, pp1049-57)
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Alzheimer Syndrome; Alzheimer-Type Dementia (ATD); Alzheimer Type Dementia (ATD); Dementia, Alzheimer-Type (ATD); Dementia, Alzheimer Type; Alzheimer Type Dementia; Senile Dementia, Alzheimer Type; Alzheimer Type Senile Dementia.
Where it fits in the MeSH classification
- Broader topics
- Dementia; Tauopathies
- See also
- Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Cerebral Amyloid Angiopathy; tau Proteins; Neurofilament Proteins; Aphasia, Primary Progressive; Kluver-Bucy Syndrome
Related concepts
- Brain
- Dementia
- Memory
- Apraxias
- Senile Plaques
- Neurofibrillary Tangles
- Neuropil Threads
Research landscape
PubMed indexes 145,267 records tagged with the MeSH heading “Alzheimer Disease” (counts retrieved 2026-10-29). 50,790 of them (35.0%) were published from 2020 onward, and the busiest period so far is 2020 onward with 50,790 records.
Reviews account for 30,766 records (21.2%) and meta-analyses for 1,981. Randomized controlled trials number 2,588 (1.8%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 20,681 |
| 2000-2009 | 28,559 |
| 2010-2019 | 45,237 |
| 2020 onward | 50,790 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 30,766 | 21.2% |
| Meta-analyses | 1,981 | 1.4% |
| Randomized controlled trials | 2,588 | 1.8% |
Method: PubMed query "Alzheimer Disease"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-29.
Reading the evidence in neuroscience
Neuroscience draws on tools with different strengths: cellular and animal work can manipulate circuits directly, while human imaging and electrophysiology observe the living brain at lower resolution. Small imaging studies are prone to false positives, and findings in animals do not always carry over to people. Clinical neurology and psychiatry rely on trials and cohort studies whose outcomes are often symptom scales. Check the species, the sample size, how the outcome was measured and whether results were replicated.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Diagnostic performance of plasma pTau217 in genetically admixed South American populations | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42693124 · DOI · PMC13542151 |
| Vulnerability of locus coeruleus connections to aging and Alzheimer's disease | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42583783 · DOI · PMC13463321 |
| Prospective study on physical activity and Alzheimer's disease-related biomarkers | 2026 | Research article Design not recorded in structured metadata | 1 | cc by PMID 42619275 · DOI · PMC13490848 |
Diagnostic performance of plasma pTau217 in genetically admixed South American populations [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Plasma pTau217 is a leading biomarker for Alzheimer's disease, but evidence from genetically admixed populations in low- and middle-income countries remains limited.
- Closing excerpt
- These findings support the use of plasma pTau217-based biomarkers in genetically admixed South American populations and in settings with limited access to CSF testing and brain imaging.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (153 words)
Plasma pTau217 is a leading biomarker for Alzheimer's disease, but evidence from genetically admixed populations in low- and middle-income countries remains limited. We evaluated the diagnostic performance of pTau217 and pTau217/Aβ42 measured using Simoa technology in memory-clinic cohorts from Brazil (Cog-Aging-Study, n = 353) and Argentina (GeNED.ar, n = 134). Here we show that both biomarkers accurately identified cerebrospinal fluid (CSF)-defined amyloid pathology in Cog-Aging-Study-Brazil and showed high concordance with clinical diagnosis across both cohorts. Classification performance was improved using two-cut-off approaches that account for diagnostic uncertainty. We further show that APOE-ε4, lower body mass index, and reduced kidney function were associated with higher pTau217 in Cog-Aging-Study-Brazil, whereas education also influenced biomarker levels in GeNED.ar-Argentina. African ancestry modified APOE-ε4 effect on CSF but not plasma biomarkers. These findings support the use of plasma pTau217-based biomarkers in genetically admixed South American populations and in settings with limited access to CSF testing and brain imaging.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42693124 · DOI · PMC13542151
Vulnerability of locus coeruleus connections to aging and Alzheimer's disease [2]
Abstract reading summary — source excerpts
- Opening excerpt
- IntroductionThe locus coeruleus (LC) is important in coordinating communication between brain regions through its widespread connections.
- Closing excerpt
- DiscussionThese findings provide new insights into LC connectivity in aging and AD, highlighting its potential role as a resilience marker against AD neurodegeneration.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (143 words)
IntroductionThe locus coeruleus (LC) is important in coordinating communication between brain regions through its widespread connections. However, the organization of its connections, and its changes with aging and Alzheimer's disease (AD), remains unclear.MethodsWe mapped whole-brain white matter connections from the LC in two independent cohorts: one spanning the adult lifespan and another covering the AD continuum.ResultsWe identified a novel dorsal-ventral organization of LC connectivity that showed changes common to aging and AD or specific to AD, was linked to gene expression patterns, and was associated with cognitive performance and tau pathology in the entorhinal cortex. We also developed an imaging marker, LC gap, capturing LC connectivity deviations associated with slower tau accumulation in cognitively normal individuals at high risk for AD.DiscussionThese findings provide new insights into LC connectivity in aging and AD, highlighting its potential role as a resilience marker against AD neurodegeneration.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42583783 · DOI · PMC13463321
Prospective study on physical activity and Alzheimer's disease-related biomarkers [3]
Abstract reading summary — source excerpts
- Opening excerpt
- IntroductionEvidence regarding the association between physical activity (PA) and Alzheimer's disease (AD)-related biomarkers is scarce and inconsistent.
- Closing excerpt
- DiscussionOur NfL and GFAP results suggest that midlife PA may reduce risk for neurodegeneration in older age via amyloid-independent mechanisms.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (156 words)
IntroductionEvidence regarding the association between physical activity (PA) and Alzheimer's disease (AD)-related biomarkers is scarce and inconsistent.MethodsAt ages 56 and 67, 564 men from the Vietnam Era Twin Study of Aging reported their PA during the preceding week from which metabolic equivalent of energy expenditure (MET) hours were determined. At age 67 we assayed plasma AD-related biomarkers (phosphorylated tau [p-tau]217, neurofilament light chain [NfL], amyloid beta (Aβ)42/40 ratio, and glial fibrillary acidic protein [GFAP]). We used generalized estimating equations to test whether PA at ages 56 or 67 was associated with these biomarkers at 67.ResultsAge 56 MET hours were inversely associated with NfL and GFAP at 67 (NfL: B = -0.10, 95% confidence interval [CI]: -0.17 to -0.03, GFAP: B = -0.08, 95% CI: -0.15 to -0.01) but were not significantly associated with p-tau217 or Aβ42/40 ratio.DiscussionOur NfL and GFAP results suggest that midlife PA may reduce risk for neurodegeneration in older age via amyloid-independent mechanisms.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42619275 · DOI · PMC13490848
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Clonal hematopoiesis is associated with protection from Alzheimer's disease [4]
- Research article The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers [5]
- Research article Gut microbiome dysbiosis in Alzheimer's disease and mild cognitive impairment: A systematic review and meta-analysis [6]
- Research article The FDA-approved anti-amyloid-β monoclonal antibodies for the treatment of Alzheimer's disease: a systematic review and meta-analysis of randomized controlled trials [7]
- Research article The GABAergic system in Alzheimer's disease: a systematic review with meta-analysis [8]
- Research article Comparative efficacy, tolerability and acceptability of donanemab, lecanemab, aducanumab and lithium on cognitive function in mild cognitive impairment and Alzheimer's disease: A systematic review and network meta-analysis [9]
References
- Martino-Adami PV, Coutinho de Alvarenga J, Freccero P, Huber H, Fernandez J, Bolaños Burgos IC, et al.. Diagnostic performance of plasma pTau217 in genetically admixed South American populations. . 2026. PMID 42693124 · DOI · PMC13542151
- Zufiria-Gerbolés B, Vereb D, Mijalkov M, Passaretti M, Volpe G, Xu Z, et al.. Vulnerability of locus coeruleus connections to aging and Alzheimer's disease. . 2026. PMID 42583783 · DOI · PMC13463321
- Iso-Markku P, Tu XM, Rissman RA, Gillespie NA, Elman JA, Fennema-Notestine C, et al.. Prospective study on physical activity and Alzheimer's disease-related biomarkers. . 2026. PMID 42619275 · DOI · PMC13490848
- Bouzid H, Belk JA, Jan M, Qi Y, Sarnowski C, Wirth S, et al.. Clonal hematopoiesis is associated with protection from Alzheimer's disease. Nat Med. 2023. PMID 37322115 · DOI · PMC10353941
- Wei BZ, Li L, Dong CW, Tan CC, Alzheimer’s Disease Neuroimaging Initiative, Xu W. The Relationship of Omega-3 Fatty Acids with Dementia and Cognitive Decline: Evidence from Prospective Cohort Studies of Supplementation, Dietary Intake, and Blood Markers. Am J Clin Nutr. 2023. PMID 37028557 · DOI · PMC10447496
- Jemimah S, Chabib CMM, Hadjileontiadis L, AlShehhi A. Gut microbiome dysbiosis in Alzheimer's disease and mild cognitive impairment: A systematic review and meta-analysis. PLoS One. 2023. PMID 37224131 · DOI · PMC10208513
- Wu W, Ji Y, Wang Z, Wu X, Li J, Gu F, et al.. The FDA-approved anti-amyloid-β monoclonal antibodies for the treatment of Alzheimer's disease: a systematic review and meta-analysis of randomized controlled trials. Eur J Med Res. 2023. PMID 38017568 · DOI · PMC10683264
- Carello-Collar G, Bellaver B, Ferreira PCL, Ferrari-Souza JP, Ramos VG, Therriault J, et al.. The GABAergic system in Alzheimer's disease: a systematic review with meta-analysis. Mol Psychiatry. 2023. PMID 37419974 · DOI
- Terao I, Kodama W. Comparative efficacy, tolerability and acceptability of donanemab, lecanemab, aducanumab and lithium on cognitive function in mild cognitive impairment and Alzheimer's disease: A systematic review and network meta-analysis. Ageing Res Rev. 2024. PMID 38253184 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-10-29.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.