Human ageing and its discontents: rethinking health, disease and intervention

Human ageing is a complex biological process characterized by age-related functional decline, resulting in increased vulnerability to illness, disease and death. Although advances in molecular gerontology have elucidated the cellular and molecular underpinnings of ageing, translating these insights into effective strategies that extend both health span and lifespan in humans remains a pressing challenge. A persistent obstacle is the absence of a coherent and operational definition of health within the field. Traditional models define health as the absence of disease or functional impairment, but this conception becomes increasingly inadequate in the context of ageing, where multimorbidity, subclinical dysfunction and frailty often occur without overt pathology. Ageing can be conceptualized as a contraction of the homeodynamic space, reflecting diminished resilience, adaptability and repair capacity. From a philosophical perspective, health may be understood as a sustained pattern of adaptive traits over time. In this review, we explore conceptual distinctions between health, illness, disease and related terms, with particular attention to clinically significant yet non-pathological states. We argue that biogerontology should adopt resilience-based and systems-level frameworks to capture the complexity of ageing and to guide the development of interventions that support functioning and quality of life across the lifespan. We also propose an integrative model that links personalized geroscience approaches with lifespan-related, behavioural and social factors to promote healthy ageing.