title: A proposed panel of biomarkers of healthy ageing.
abstract: BACKGROUND
  There is no criterion reference for assessing healthy ageing and this creates difficulties when conducting and comparing research on ageing across studies. A cardinal feature of ageing is loss of function which translates into wide-ranging consequences for the individual and for family, carers and society. We undertook comprehensive reviews of the literature searching for biomarkers of ageing on five ageing-related domains including physical capability and cognitive, physiological and musculoskeletal, endocrine and immune functions. Where available, we used existing systematic reviews, meta-analyses and other authoritative reports such as the recently launched NIH Toolbox for assessment of neurological and behavioural function, which includes test batteries for cognitive and motor function (the latter described here as physical capability). We invited international experts to comment on our draft recommendations. In addition, we hosted an experts workshop in Newcastle, UK, on 22-23 October 2012, aiming to help capture the state-of-the-art in this complex area and to provide an opportunity for the wider ageing research community to critique the proposed panel of biomarkers.
  
  
  CONCLUSIONS
  Here we have identified important biomarkers of healthy ageing classified as subdomains of the main areas proposed. Cardiovascular and lung function, glucose metabolism and musculoskeletal function are key subdomains of physiological function. Strength, locomotion, balance and dexterity are key physical capability subdomains. Memory, processing speed and executive function emerged as key subdomains of cognitive function. Markers of the HPA-axis, sex hormones and growth hormones were important biomarkers of endocrine function. Finally, inflammatory factors were identified as important biomarkers of immune function. We present recommendations for a panel of biomarkers that address these major areas of function which decline during ageing. This biomarker panel may have utility in epidemiological studies of human ageing, in health surveys of older people and as outcomes in intervention studies that aim to promote healthy ageing. Further, the inclusion of the same common panel of measures of healthy ageing in diverse study designs and populations may enhance the value of those studies by allowing the harmonisation of surrogate endpoints or outcome measures, thus facilitating less equivocal comparisons between studies and the pooling of data across studies.
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine and Newcastle University Institute for Ageing, Newcastle University, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK. jose.lara@newcastle.ac.uk.
authors.forename: Jose
authors.initials: J
authors.lastname: Lara
authors.affiliation: MRC Unit for Lifelong Health and Ageing, MRC Unit for Lifelong Health and Ageing at UCL, 33 Bedford Place, London, WC1B 5JU, UK. rachel.cooper@ucl.ac.uk.
authors.forename: Rachel
authors.initials: R
authors.lastname: Cooper
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK. jack@tinderboxproject.co.uk.
authors.forename: Jack
authors.initials: J
authors.lastname: Nissan
authors.affiliation: School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. a.t.ginty@bham.ac.uk.
authors.forename: Annie T
authors.initials: AT
authors.lastname: Ginty
authors.affiliation: University of Cambridge, Addenbrooke's University Hospital, Cambridge, UK. kk101@medschl.cam.ac.uk.
authors.forename: Kay-Tee
authors.initials: KT
authors.lastname: Khaw
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, University of Edinburgh, 7 George Square, Edinburgh, EH8 9JZ, UK. iand@exseed.ed.ac.uk.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
authors.affiliation: MRC-ARUK Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. j.m.lord@bham.ac.uk.
authors.forename: Janet M
authors.initials: JM
authors.lastname: Lord
authors.affiliation: MRC Unit for Lifelong Health and Ageing, MRC Unit for Lifelong Health and Ageing at UCL, 33 Bedford Place, London, WC1B 5JU, UK. d.kuh@ucl.ac.uk.
authors.forename: Diana
authors.initials: D
authors.lastname: Kuh
authors.affiliation: Human Nutrition Research Centre, Institute of Cellular Medicine and Newcastle University Institute for Ageing, Newcastle University, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne, NE4 5PL, UK. john.mathers@newcastle.ac.uk.
authors.forename: John C
authors.initials: JC
authors.lastname: Mathers
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D015415:Biomarkers / Q000032:analysis*; D006801:Humans
chemical_list: D015415:Biomarkers