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 (571 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
The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
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: Biological Aging; Aging, Biological; Senescence.
Where it fits in the MeSH classification
- Broader topics
- Growth and Development
- Narrower topics
- Cellular Senescence; Cognitive Aging; Immunosenescence; Longevity
- See also
- Skin Aging; Cellular Senescence; Plant Senescence
Research landscape
PubMed indexes 326,482 records tagged with the MeSH heading “Aging” (counts retrieved 2026-10-31). 62,673 of them (19.2%) were published from 2020 onward, and the busiest period so far is through 1999 with 109,563 records.
Reviews account for 48,005 records (14.7%) and meta-analyses for 1,262. Randomized controlled trials number 3,817 (1.2%) 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 | 109,563 |
| 2000-2009 | 65,257 |
| 2010-2019 | 88,989 |
| 2020 onward | 62,673 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 48,005 | 14.7% |
| Meta-analyses | 1,262 | 0.4% |
| Randomized controlled trials | 3,817 | 1.2% |
Method: PubMed query "Aging"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in anatomy and physiology
Anatomy describes how body structures are built and physiology describes how they normally work, so most findings here are descriptive or mechanistic rather than evidence about treatment. Much of what is known comes from dissection, imaging, tissue studies and experiments in animals, and measurements in healthy volunteers can differ from those in people with disease or at different ages. Normal ranges vary between individuals and populations. Check whether a result was measured in people or in another species, the age and health of the participants, and the method used.
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 |
|---|---|---|---|---|
| Dynamics of blood NAD and glutathione in health, disease, aging, and under NAD+-booster treatment | 2026 | Research article Design not recorded in structured metadata | 5 | cc by PMID 42628241 · DOI · PMC13524494 |
| Preserved cerebellar functions despite structural degeneration in older adults | 2026 | Research article Design not recorded in structured metadata | 4 | cc by PMID 42703946 · DOI · PMC13549622 |
| Insights into longevity and virus-driven adaptation from Myotis bat genomes | 2026 | Research article Design not recorded in structured metadata | 3 | cc by PMID 42649300 · DOI · PMC13626957 |
Dynamics of blood NAD and glutathione in health, disease, aging, and under NAD+-booster treatment [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Nicotinamide adenine dinucleotides (NAD+, NADH, NADP+ and NADPH) and glutathione (GSH and GSSG) metabolites are vital regulators of redox state, enzyme functions, and metabolic flux in hundreds of cellular metabolic reactions.
- Closing excerpt
- The evidence highlights the potential of redox profiling as an indicator of probable pathology and as a measure of treatment response.
- 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 (194 words)
Nicotinamide adenine dinucleotides (NAD+, NADH, NADP+ and NADPH) and glutathione (GSH and GSSG) metabolites are vital regulators of redox state, enzyme functions, and metabolic flux in hundreds of cellular metabolic reactions. NAD+/NADH ratio increases during fasting and has been associated with health outcomes in model systems. A low ratio occurs in specific diseases, treated with high-dose B3-vitamin forms, so-called NAD+-boosters. Still, neither healthy human values nor NAD+ booster-treated or disease-related levels of NAD(P)(H) or glutathione have been established in humans. Here, we report a standardized workflow of enzymatic cycling assays to quantitatively measure NAD+, NADH, NADP+, NADPH, GSH, and GSSG from a single whole-blood sample. In the blood of a healthy population aged 18-70 years, these metabolites follow a normal distribution and remain unchanged during aging. High-dose nicotinic acid, a B3 vitamin, resulted in 4-6-fold increase of blood NAD+ in healthy individuals, suggesting the need for personalized dosing and follow-up in treatment and drug trials. Our data also indicate disease-dependent "redox fingerprints" of NAD and glutathione forms in different degenerative diseases, including cancers. The evidence highlights the potential of redox profiling as an indicator of probable pathology and as a measure of treatment response.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42628241 · DOI · PMC13524494
Preserved cerebellar functions despite structural degeneration in older adults [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Aging is frequently perceived negatively due to its association with declines in brain and motor function yet not all aspects of brain function are equally affected.
- Closing excerpt
- Together, these findings indicate that cerebellar function is largely preserved despite pronounced structural degeneration, providing compelling evidence for the cerebellum's remarkable functional resilience.
- 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 (181 words)
Aging is frequently perceived negatively due to its association with declines in brain and motor function yet not all aspects of brain function are equally affected. The cerebellum, a brain region closely linked to motor control, undergoes clear structural changes with age, but the impact of this degeneration on cerebellar function remains debated. The present study thoroughly investigates the impact of age on cerebellar function by measuring cerebellar motor and cognitive performance across the lifespan in 50 young adults (20-35 years), 80 older adults (55-70 years), and 30 older-old adults (over 80 years). Participants completed a test battery comprising seven motor control tasks and one cognitive task each designed to probe both cerebellar-specific and general sensorimotor function. Our results revealed that, despite age-related changes in cerebellar structure, cerebellar-specific functions remained intact in older adults compared to young adults, even among those above 80 years old. In contrast, general sensorimotor measures showed a clear pattern of decline with age. Together, these findings indicate that cerebellar function is largely preserved despite pronounced structural degeneration, providing compelling evidence for the cerebellum's remarkable functional resilience.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42703946 · DOI · PMC13549622
Insights into longevity and virus-driven adaptation from Myotis bat genomes [3]
Abstract reading summary — source excerpts
- Opening excerpt
- The genus Myotis is one of the largest clades of bats, and it exhibits some of the most extreme variation in lifespans among mammals, alongside unique adaptations to viral tolerance and immune defence1-3.
- Closing excerpt
- Together, our results suggest that bats' remarkable longevity and immunity are linked through pleiotropic adaptations to viruses and ageing-related disease.
- 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 (196 words)
The genus Myotis is one of the largest clades of bats, and it exhibits some of the most extreme variation in lifespans among mammals, alongside unique adaptations to viral tolerance and immune defence1-3. Here, to study the evolution of these phenotypes, we generated cell lines and near-complete genome assemblies for eight closely related Myotis species. Using genome-wide screens of positive selection, analyses of structural variation and functional experiments in primary cells, we identify patterns of adaptation contributing to longevity, cancer resistance and viral interactions. We demonstrate distinct modes of adaptation to DNA and RNA viruses compared with all other mammals, with bats exhibiting genome-wide over-representation of positive selection for DNA-virus-interacting proteins and elevated rates of copy-number variation for RNA-virus-interacting proteins. Characterization of Myotis-specific duplications of the key immune factor EIF2AK2 (also known as PKR) reveals multiple ancient segregating trans-species copy-number polymorphisms. We show that the recurrent evolution of longevity seen in Myotis is associated with positive selection in cancer pathways, and demonstrate a unique response to DNA damage in primary cells of the long-lived Myotis lucifugus. Together, our results suggest that bats' remarkable longevity and immunity are linked through pleiotropic adaptations to viruses and ageing-related disease.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42649300 · DOI · PMC13626957
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 Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis [4]
- Research article DNA methylation-based measures of biological age: meta-analysis predicting time to death [5]
- Research article Frailty index as a predictor of mortality: a systematic review and meta-analysis [6]
- Research article A re-examination of Montreal Cognitive Assessment (MoCA) cutoff scores [7]
- Research article Clinical Significance of Magnetic Resonance Imaging Markers of Vascular Brain Injury: A Systematic Review and Meta-analysis [8]
- Research article Sex differences in frailty: A systematic review and meta-analysis [9]
References
- Euro L, Haimilahti K, Jansson S, Forsström S, Buzkova J, Suomalainen A. Dynamics of blood NAD and glutathione in health, disease, aging, and under NAD+-booster treatment. . 2026. PMID 42628241 · DOI · PMC13524494
- de Witte A, Matthijs A, Parrell B, Mantini D, Gooijers J, Orban de Xivry JJ. Preserved cerebellar functions despite structural degeneration in older adults. . 2026. PMID 42703946 · DOI · PMC13549622
- Vazquez JM, Lauterbur ME, Mottaghinia S, Gaucherand L, Maesen S, Singer M, et al.. Insights into longevity and virus-driven adaptation from Myotis bat genomes. . 2026. PMID 42649300 · DOI · PMC13626957
- Flaxman SR, Bourne RRA, Resnikoff S, Ackland P, Braithwaite T, Cicinelli MV, et al.. Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. Lancet Glob Health. 2017. PMID 29032195 · DOI
- Chen BH, Marioni RE, Colicino E, Peters MJ, Ward-Caviness CK, Tsai PC, et al.. DNA methylation-based measures of biological age: meta-analysis predicting time to death. Aging (Albany NY). 2016. PMID 27690265 · DOI · PMC5076441
- Kojima G, Iliffe S, Walters K. Frailty index as a predictor of mortality: a systematic review and meta-analysis. Age Ageing. 2018. PMID 29040347 · DOI
- Carson N, Leach L, Murphy KJ. A re-examination of Montreal Cognitive Assessment (MoCA) cutoff scores. Int J Geriatr Psychiatry. 2018. PMID 28731508 · DOI
- Debette S, Schilling S, Duperron MG, Larsson SC, Markus HS. Clinical Significance of Magnetic Resonance Imaging Markers of Vascular Brain Injury: A Systematic Review and Meta-analysis. JAMA Neurol. 2019. PMID 30422209 · DOI · PMC6439887
- Gordon EH, Peel NM, Samanta M, Theou O, Howlett SE, Hubbard RE. Sex differences in frailty: A systematic review and meta-analysis. Exp Gerontol. 2017. PMID 28043934 · 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 2026-10-31.
See how EvidenceLib is built. Spotted an error? Email support@evidencehelix.com.
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.