Concepts and definitions of healthy ageing: a systematic review and synthesis of theoretical models

Background: Healthy ageing (HA) has been defined using multiple approaches. We aim to produce a comprehensive overview and analysis of the theoretical models underpinning this concept and its associated normative terms and definitions. Methods: We conducted a systematic review of peer-reviewed HA models in Embase.com, Medline(Ovid), Cochrane CENTRAL, CINAHL, PsycINFO, and Web of Science until August 2022. Original theoretical papers, concept analyses, and reviews that proposed new models were included. Operational models/definitions, lifespan development psychology theories and mechanisms of ageing were excluded. We followed an iterative approach to extract the models’ characteristics and thematically analyze them based on the approach of Walker and Avant. The protocol was registered in PROSPERO(CRD42021238796). Results: Out of 10, 741 records, we included 59 papers comprising 65 models/ definitions, published in English (1960–2022) from 16 countries in Europe, Asia, and America. Human ageing was described using 12 normative terms, mainly (models (%)): successful (34 (52%)), healthy (eight (12%)), well (five (8%)), and active (four (6%)). We identified intrinsic/extrinsic factors interacting throughout the life course, adaptive processes as attributes, and outcomes describing patterns of ageing across objective and subjective dimensions (number of models/definitions): cognitive(62), psychological(53), physical (49), social (49), environmental (19), spiritual (16), economic (13), cultural (eight), political (six), and demographic (four) dimensions. Three types of models emerged: health-state outcomes (three), adaptations across the life course (31), or a combination of both (31). Two additional sub-classifications emphasized person-environment congruence and health promotion. Conclusions:HA is heterogeneously termed and conceptualized multidimensionally as adaptive processes of dynamic person-environment interactions to ageing, health-state outcomes, or both. Congruence with the living environment and health promotion/empowerment are emphasized. Our model classification provides a basis for harmonizing conceptual terms and dimensions that can guide research and comparisons of empirical Findings. This would inform social and health policies enabling HA for populations in various contexts.