title: Is telomere length a biomarker for aging: cross-sectional evidence from the west of Scotland?
abstract: BACKGROUND
  The search for biomarkers of aging (BoAs) has been largely unsuccessful to-date and there is widespread skepticism about the prospects of finding any that satisfy the criteria developed by the American Federation of Aging Research. This may be because the criteria are too strict or because a composite measure might be more appropriate. Telomere length has attracted a great deal of attention as a candidate BoA. We investigate whether it meets the criteria to be considered as a single biomarker of aging, and whether it makes a useful contribution to a composite measure.
  
  
  RESULTS
  Using data from a large population based study, we show that telomere length is associated with age, with several measures of physical and cognitive functioning that are related to normal aging, and with three measures of overall health. In the majority of cases, telomere length adds predictive power to that of age, although it was not nearly as good a predictor overall. We used principal components analysis to form two composites from the measures of functioning, one including telomere length and the other not including it. These composite BoAs were better predictors of the health outcomes than chronological age. There was little difference between the two composites.
  
  
  CONCLUSIONS
  Telomere length does not satisfy the strict criteria for a BoA, but does add predictive power to that of chronological age. Equivocal results from previous studies might be due to lack of power or the choice of measures examined together with a focus on single biomarkers. Composite biomarkers of aging have the potential to outperform age and should be considered for future research in this area.
authors.affiliation: Social & Public Health Sciences Unit, Medical Research Council, Glasgow, United Kingdom. G.Der@sphsu.mrc.ac.uk
authors.forename: Geoff
authors.initials: G
authors.lastname: Der
authors.forename: G David
authors.initials: GD
authors.lastname: Batty
authors.forename: Michaela
authors.initials: M
authors.lastname: Benzeval
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Green
authors.forename: Liane
authors.initials: L
authors.lastname: McGlynn
authors.forename: Alan
authors.initials: A
authors.lastname: McIntyre
authors.forename: Tony
authors.initials: T
authors.lastname: Robertson
authors.forename: Paul G
authors.initials: PG
authors.lastname: Shiels
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000235:genetics*; D015415:Biomarkers; D003071:Cognition / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D025341:Principal Component Analysis; D012606:Scotland; D016615:Telomere / Q000737:chemistry* / Q000235:genetics; D059505:Telomere Homeostasis / Q000235:genetics*
chemical_list: D015415:Biomarkers