title: Depression and telomere length: A meta-analysis.
abstract: BACKGROUND
  Several recent studies have investigated the relationship between telomere length and depression with inconsistent results. This meta-analysis examined whether telomere length and depression are associated and explored factors that might affect this association.
  
  
  METHODS
  Studies measuring telomere length in subjects with clinically significant unipolar depression were included. A comprehensive search strategy identified studies in PubMed, MEDLINE, PsycINFO, Global Health, The Cochrane Library, and Web of Science. A structured data abstraction form was used and studies were appraised for inclusion or exclusion using a priori conditions. Analyses were conducted using standardized mean differences in a continuous random effects model.
  
  
  RESULTS
  Thirty-eight studies (N=34,347) met the inclusion criteria. The association between depression and telomere length was significant, with a Cohen's d effect size of -0.205 (p<0.0001, I(2)=42%). Depression severity significantly associated with telomere length (p=0.03). Trim and fill analysis indicated the presence of publication bias (p=0.003), but that the association remained highly significant after accounting for the bias. Subgroup analysis revealed depression assessment tools, telomere measurement techniques, source tissue and comorbid medical conditions significantly affected the relationship.
  
  
  CONCLUSIONS
  Other potentially important sub-groups, including antidepressant use, have not been investigated in sufficient detail or number yet and thus were not addressed in this meta-analysis.
  
  
  CONCLUSIONS
  There is a negative association between depression and telomere length. Further studies are needed to clarify potential causality underlying this association and to elucidate the biology linking depression and this cellular marker of stress exposure and aging.
authors.affiliation: Mood Disorders Research Program and Laboratory for Clinical and Translational Neuroscience, Butler Hospital, Providence, RI, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA. Electronic address: Kathryn_Ridout@Brown.edu.
authors.forename: Kathryn K
authors.initials: KK
authors.lastname: Ridout
authors.affiliation: Mood Disorders Research Program and Laboratory for Clinical and Translational Neuroscience, Butler Hospital, Providence, RI, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Ridout
authors.affiliation: Mood Disorders Research Program and Laboratory for Clinical and Translational Neuroscience, Butler Hospital, Providence, RI, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Price
authors.affiliation: Molecular and Behavioral Neuroscience Institute and Department of Psychiatry, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Srijan
authors.initials: S
authors.lastname: Sen
authors.affiliation: Mood Disorders Research Program and Laboratory for Clinical and Translational Neuroscience, Butler Hospital, Providence, RI, USA; Department of Psychiatry and Human Behavior, Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: Audrey R
authors.initials: AR
authors.lastname: Tyrka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003863:Depression / Q000235:genetics*; D003866:Depressive Disorder / Q000235:genetics*; D005260:Female; D005821:Genetic Techniques; D006801:Humans; D008297:Male; D008875:Middle Aged; D016615:Telomere / Q000473:pathology*; D055815:Young Adult
keywords: Depression; Major depressive disorder; Meta-analysis; Telomere