Key points from the graphic
- The graphic summarises standard definitions of ageing and senescence agreed by the International Consortium to Classify Ageing-Related Pathologies (ICCARP), formed in 2023.
- Senescence, at its broadest, is a decline in normal function with chronological age. The graphic stresses that it is not inherently pathological.
- Cellular senescence is a state of cell cycle arrest. Short term (acute) senescence is usually physiological and helps development and repair; when senescent cells build up and persist (chronic senescence) it is pathological.
- The same idea is applied at every scale: tissue, organ, system and the whole organism.
- Normative ageing is the expected path of declining function in a population; a faster decline can be regarded as pathological.
Senescence vs aging, the graphic in text
Title: “Defining Senescence”, with background words “old age”, “cell cycle arrest”, “functional decline” and the pronunciation [sɪˈnesəns]. The text below follows the graphic section by section.
Introduction. “Ageing-related diseases are a growing problem. In the US, 95% of persons over 60 have at least one chronic health condition [1], and globally, this group will double by 2050 [2].” A ring chart reads “95%, Older adults with chronic conditions”.
Supporting healthier ageing. In 2023 over 300 scientists and clinicians formed ICCARP to help healthcare systems prepare for an ageing population and to enable earlier diagnosis and treatment. Because ageing terms were understood differently in different fields, standard definitions were created and are summarised on the graphic.
Normative ageing. A hand drawn graph plots functional capacity against age, with three curves labelled accelerated ageing (falling earliest), normative ageing and healthy ageing (falling latest). Definition: “The expected trajectory in the loss of functional capacity in a population. An accelerated deviation from normative ageing can be regarded as pathological.”
Senescence. “At the broadest level, senescence refers to a decline in normal function with chronological age that can induce pathologies, though senescence is not inherently pathological.”
Cellular senescence. A state of cell cycle arrest caused by excessive proliferation or stressors, marked by changes (for example altered metabolism and SASP) that distinguish senescent cells from quiescent or terminally differentiated cells. Senescent cells can be detected throughout life. Acute senescence is typically physiological, with functions in development and repair; when the cells accumulate and persist, chronic senescence results, which is associated with deteriorating function and is pathological. A diagram runs from “Stimulus / Stressor” to “Acute Senescence”, then branches to “Physiological Senescence (repair)” and “Pathological Senescence (persistent damage)”.
Physiological vs pathological senescence. Across all forms (cellular, tissue, organ, system and organismal) senescence can be physiological or pathological.
Tissue and organ senescence. Tissue senescence is the age related decline in tissue structure or function, often due to senescent cells or factors such as aberrations in proteostasis or changes in the extracellular matrix. Organ senescence is a similar decline in organs, driven by tissue senescence; it can lead to pathologies such as cognitive decline or adaptations such as cardiac hypertrophy, but may also be normative, as in post menopausal uterine senescence.
Systems senescence. An ageing related decline in the functional capacity of a constellation of soluble factors, cells, tissues or organs that work together for a specific function, which may arise from cellular, tissue or organ senescence.
Organismal senescence. The gradual decline in physiological function and biological integrity between cells, tissues, organs and systems as an organism ages. It is intrinsically related to lifespan and results from cellular, tissue, organ or systems senescence, so its hallmarks should be defined by those parameters.
Footer. “For full defintions, please see: Short et al. (2024). International Consortium to Classify Ageing-Related Pathologies (ICCARP) Senescence Definitions: Achieving International Consensus. doi:10.6084/m9.figshare.27969546”. References: [1] ncoa.org, “the top 10 most common chronic conditions in older adults”; [2] doi.org/10.1002/app5.153. “Research funded by: Impetus Grants”.
What the ICCARP paper adds
The definitions were agreed by ICCARP members at consensus meetings in 2024 and published as a letter in GeroScience, led by Emma Short and Robert Huckstepp [1]. The consortium is led by Cardiff Metropolitan University and was set up after the World Health Organization decided to classify age related aetiologies [1]. The preprint cited on the graphic says the project is funded by an Impetus grant from the Norn group [2].
The paper gives more detail than the graphic. It says growth arrest in cellular senescence is mediated mainly by the CDK inhibitors p16 and p21, that SASP stands for the senescence associated secretory phenotype, and that senescent cells promote their own removal by immune cells to maintain tissue integrity [1]. It gives kidney function as an example of pathological senescence, where p21 positive senescent cells are linked to reduced regenerative capacity with age and after injury [1]. Physiological senescence, it says, is usually short term because it has a defined purpose and stops once that purpose is met [1].
Notes on this infographic
- The 95% figure has changed. The NCOA page the graphic cites for “95% of persons over 60” now says that 93% of adults aged 65 and older have at least one chronic condition and 79% have two or more, citing research published in 2025 [3].
- Doubling by 2050. The WHO says that by 2050 the world’s population of people aged 60 and older will double to 2.1 billion [4]. That supports the graphic’s second claim, although the graphic phrases it as the group with chronic conditions.
- Citation date. The graphic cites “Short et al. (2024)”, the preprint posted on Figshare in December 2024 [2]. The peer reviewed version appeared later in GeroScience [1].
- Spelling. The footer prints “defintions”; the correct spelling is definitions.
- Not medical advice. The graphic and this page explain terminology. They say nothing about treatments for ageing.
Questions about senescence and ageing
What is the difference between senescence and aging?
ICCARP uses the two words differently. Normative ageing is the expected trajectory of ageing based on data from a particular population. Senescence is the decline in normal functioning that occurs with chronological age, which can be described at the level of cells, tissues, organs, systems or the whole organism, and which can be physiological or pathological [1].
What is cellular senescence?
ICCARP defines cellular senescence as a state of indefinite cell cycle arrest that arises from exhaustive cell proliferation or from stressors such as genotoxic and oxidative agents, sustained nutrient deprivation and oncogene activation [1]. Senescent cells also change in shape, metabolism and secretions, which distinguishes them from resting or fully differentiated cells [1].
Sources
- Short E, Huckstepp RTR, et al., International Consortium to Classify Ageing-related Pathologies (ICCARP) senescence definitions: achieving international consensus, GeroScience (PubMed Central).
- Short E, Huckstepp R, et al., ICCARP Senescence Definitions: Achieving International Consensus, preprint, Figshare, 5 December 2024.
- National Council on Aging, Top 10 Chronic Conditions Affecting Older Adults.
- World Health Organization, Ageing and health, fact sheet.
- ICCARP, International Consortium to Classify Ageing-Related Pathologies.
Last reviewed 30 October 2026
