International Consortium to Classify Ageing-Related Pathologies (ICCARP) definitions of Senescence

The aim of the ICCARP is to develop a systematic and comprehensive classification system for ageing-related changes including pathologies, diseases, and syndromes. Currently, the ICCARP is in the process of identifying all phenomena that meet the criteria for ageing-related pathologies, to develop proposals for grouping and naming them within a comprehensive classification system. However, during the course of this project, it became evident that certain terms, specifically relating to ‘senescence’, were interpreted and understood in multiple ways, often dependent upon the professional background of an expert and the context in which the term was being used.

To achieve our goals, it is vital that we use a universal language when naming and proposing ageing-related changes to provide a clear, unambiguous understanding of the changes and their underlying contribution to maintaining or degrading organismal integrity (physiology versus pathology). Furthermore, establishing clear nomenclature will be advantageous in the wider efforts to unify the study of ageing, and to better align research and clinical practice. The purpose of this letter soon to be published in the journal, Geroscience, is to explicitly state the definitions primarily relating to ‘senescence’ that will be used by the ICCARP, as agreed by ICCARP members through consensus meetings in 2024. The terms that will be defined are:1. Normative ageing; 2. Senescence; 3. Cellular senescence, including acute and chronic senescence; 4. Physiological senescence; 5. Pathological senescence; 6. Tissue senescence; 7. Organ senescence; 8. Systems senescence; 9. Organismal senescence.