Hallmarks of Aging

The framework is used to organize a complicated field into categories such as genomic instability, telomere attrition, epigenetic alteration, loss of protein quality control, altered nutrient sensing, mitochondrial changes, cellular senescence, stem-cell exhaustion, and changed communication among cells. Later discussions have expanded or reorganized parts of the framework as the field develops.

A hallmark is a conceptual category, not a routine diagnosis and not a score that can be read directly from one consumer test. Processes interact across tissues and time. For example, mitochondrial function, autophagy, DNA methylation, and cellular senescence connect through multiple pathways, but measuring one marker does not quantify an individual's entire ageing process.

The framework is useful for asking research questions and mapping relationships among mechanisms. Translating a mechanism into safe, effective clinical action is a separate step that requires evidence about a specific intervention and outcome. This entry explains the vocabulary without implying that a commercial panel measures or changes all hallmarks.

The categories operate at different biological scales, from molecules and organelles to communication across tissues. Their boundaries can overlap because one event may influence several hallmarks at once. The framework is therefore better viewed as a map of connected questions than as independent boxes that can each be scored and added together.