title: Longitudinal changes in leukocyte telomere length and mortality in humans.
abstract: BACKGROUND
  Leukocyte telomere length (LTL) ostensibly shortens with age and has been moderately associated with mortality. In humans, these findings have come almost solely from cross-sectional studies. Only recently has LTL shortening within individuals been analyzed in longitudinal studies. Such studies are relevant to establish LTL dynamics as biomarkers of mortality as well as to disentangle the causality of telomeres on aging.
  
  
  METHODS
  We present a large longitudinal study on LTL and human mortality, where the 10-year change of LTL is analyzed in 1,356 individuals aged 30-70 years.
  
  
  RESULTS
  We find age, smoking status, and alcohol consumption to be associated with LTL attrition and confirm a strong association with baseline LTL. The latter association might be an epiphenomenon of regression to the mean. We do not find an association of mortality with either absolute LTL or LTL attrition. Further, we show that DNA quality has an impact on TS ratios.
  
  
  CONCLUSIONS
  This study establishes that certain lifestyle factors influence LTL dynamics. However, it questions the applicability of LTL dynamics as a predictor of mortality. We suggest cautiousness when assessing actual LTL attrition due to the need for high-quality DNA and the phenomena of regression to the mean.
authors.affiliation: Danish Aging Research Center, University of Southern Denmark, JB Winslowsvej 9B, DK-5000 Odense C, Denmark. laila.bendix@slb.regionsyddanmark.dk.
authors.forename: Laila
authors.initials: L
authors.lastname: Bendix
authors.forename: Mikael
authors.initials: M
authors.lastname: Thinggaard
authors.forename: Mogens
authors.initials: M
authors.lastname: Fenger
authors.forename: Steen
authors.initials: S
authors.lastname: Kolvraa
authors.forename: Kirsten
authors.initials: K
authors.lastname: Avlund
authors.forename: Allan
authors.initials: A
authors.lastname: Linneberg
authors.forename: Merete
authors.initials: M
authors.lastname: Osler
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000428:Alcohol Drinking; D005260:Female; D006304:Health Status; D006801:Humans; D007962:Leukocytes / Q000473:pathology*; D008019:Life Style; D008136:Longevity / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking; D012959:Socioeconomic Factors; D059506:Telomere Shortening / Q000502:physiology*
keywords: Biomarkers; DNA damage and repair; Epidemiology; Longevity