Ageing

Ageing refers to the accumulation of changes over time that lead to a progressive decline in physiological function and an increased vulnerability to disease and death. It is often distinguished from chronological age, the number of years a person has lived, with biological ageing describing the functional changes that occur at the cellular and organismal levels. Ageing occurs across all living organisms and is a major risk factor for many chronic conditions.

Biological mechanisms of ageing include cellular senescence, in which cells permanently stop dividing; telomere shortening; accumulation of DNA damage; epigenetic alterations; mitochondrial dysfunction; loss of proteostasis; stem cell exhaustion; and altered intercellular communication. These processes interact to reduce tissue resilience and regenerative capacity.

There is substantial variation in how ageing manifests between individuals and species, influenced by genetics, lifestyle, and environment. Researchers measure ageing with biomarkers, functional tests, and composite indices. Epigenetic clocks and frailty measures are examples. Lifespan and healthspan may diverge, and much effort in research seeks to extend healthspan, the period of life spent in good health.

Interventions to support healthy ageing emphasize lifestyle factors such as regular physical activity, a balanced diet, avoidance of smoking, and moderate alcohol consumption; preventive healthcare including vaccination; and emerging medical strategies such as senolytics or therapies that target metabolic and regenerative pathways. Societal implications include aging populations, greater demand for long-term care, and policy considerations to sustain healthcare and pension systems.