title: Successful ageing: A study of the literature using citation network analysis.
abstract: BACKGROUND
  Ageing is accompanied by an increased risk of disease and a loss of functioning on several bodily and mental domains and some argue that maintaining health and functioning is essential for a successful old age. Paradoxically, studies have shown that overall wellbeing follows a curvilinear pattern with the lowest point at middle age but increases thereafter up to very old age.
  
  
  OBJECTIVE
  To shed further light on this paradox, we reviewed the existing literature on how scholars define successful ageing and how they weigh the contribution of health and functioning to define success.
  
  
  METHODS
  We performed a novel, hypothesis-free and quantitative analysis of citation networks exploring the literature on successful ageing that exists in the Web of Science Core Collection Database using the CitNetExplorer software. Outcomes were visualized using timeline-based citation patterns. The clusters and sub-clusters of citation networks identified were starting points for in-depth qualitative analysis.
  
  
  RESULTS
  Within the literature from 1902 through 2015, two distinct citation networks were identified. The first cluster had 1146 publications and 3946 citation links. It focused on successful ageing from the perspective of older persons themselves. Analysis of the various sub-clusters emphasized the importance of coping strategies, psycho-social engagement, and cultural differences. The second cluster had 609 publications and 1682 citation links and viewed successful ageing based on the objective measurements as determined by researchers. Subsequent sub-clustering analysis pointed to different domains of functioning and various ways of assessment.
  
  
  CONCLUSIONS
  In the current literature two mutually exclusive concepts of successful ageing are circulating that depend on whether the individual himself or an outsider judges the situation. These different points of view help to explain the disability paradox, as successful ageing lies in the eyes of the beholder.
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark. Electronic address: saku@sund.ku.dk.
authors.forename: Sasmita
authors.initials: S
authors.lastname: Kusumastuti
authors.affiliation: Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark; Department of Surgery, Section of Geriatric Oncology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Marloes G M
authors.initials: MG
authors.lastname: Derks
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Siri
authors.initials: S
authors.lastname: Tellier
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Ezio
authors.initials: E
authors.lastname: Di Nucci
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Rikke
authors.initials: R
authors.lastname: Lund
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Erik Lykke
authors.initials: EL
authors.lastname: Mortensen
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark; Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Rudi G J
authors.initials: RG
authors.lastname: Westendorp
mesh_terms: D000223:Adaptation, Psychological; D000375:Aging; D006801:Humans; D010549:Personal Satisfaction; D011642:Publications
keywords: Emic; Etic; Health; Old age; Successful ageing; Wellbeing