title: The Association Between Midlife Physical Activity and Depressive Symptoms in Late Life: Age Gene/Environment Susceptibility-Reykjavik Study.
abstract: BACKGROUND
  There is little evidence on the long-term association between physical activity (PA) and depressive symptoms in old age. We examined the association of midlife PA and depressive symptoms in late life.
  
  
  METHODS
  A large community-based population residing in Reykjavik, Iceland, participated in a longitudinal study with an average of 25 years of follow up. Midlife PA was categorized as active and inactive groups (n = 4,140, Active = 1,292, Inactive = 2,848, mean age 52±7 years). The main outcome had six or higher depressive symptoms assessed by the 15-item Geriatric Depression scale. Participants who had a history of depression (n = 226), and were diagnosed with dementia (n = 393), and had incomplete cognitive data (n = 595) and incomplete analytical data (n = 422) were excluded. Level of weekly PA was ascertained by a questionnaire at midlife. Depressive symptoms were assessed on average 25 (±4) years later.
  
  
  RESULTS
  After controlling for demographic and health-related risk factors, those who were active at midlife were less likely to have high level of depressive symptomatology (6 or higher Geriatric Depression scale scores, odds ratio = 0.58, 95% confidence interval: 0.41-0.83, p < .005) compared with those who were inactive in midlife. After full adjustment of three domains of late-life cognitive function the results remained significant (odds ratio = 0.61, 95% confidence interval: 0.43-0.86, p = .005).
  
  
  CONCLUSIONS
  Our study shows that midlife PA is associated with lower depressive symptoms 25 years later. Participating in regular PA in midlife may improve mental health in late life.
authors.affiliation: Icelandic Gerongological Research Center, National University Hospital of Iceland, Reykjavik. Department of Sport Science, School of Science and Engineering, Reykjavik University, Iceland. changmilan@gmail.com.
authors.forename: Milan
authors.initials: M
authors.lastname: Chang
authors.affiliation: Icelandic Gerongological Research Center, National University Hospital of Iceland, Reykjavik. Faculty of Medicine, University of Iceland, Reykjavik.
authors.forename: Jon
authors.initials: J
authors.lastname: Snaedal
authors.affiliation: Icelandic Gerongological Research Center, National University Hospital of Iceland, Reykjavik.
authors.forename: Bjorn
authors.initials: B
authors.lastname: Einarsson
authors.affiliation: Icelandic Gerongological Research Center, National University Hospital of Iceland, Reykjavik.
authors.forename: Sigurbjorn
authors.initials: S
authors.lastname: Bjornsson
authors.affiliation: Division of Geriatric Medicine and Meyers Primary Care Institute, University of Massachusetts Medical School, Worcester.
authors.forename: Jane S
authors.initials: JS
authors.lastname: Saczynski
authors.affiliation: Icelandic Heart Association, Kopavogur. Faculty of Science, University of Iceland, Reykjavik.
authors.forename: Thor
authors.initials: T
authors.lastname: Aspelund
authors.affiliation: Laboratory of Epidemiology and Population Science, National Institute on Aging, Bethesda, Maryland.
authors.forename: Melissa
authors.initials: M
authors.lastname: Garcia
authors.affiliation: Faculty of Medicine, University of Iceland, Reykjavik. Icelandic Heart Association, Kopavogur.
authors.forename: Vilmundur
authors.initials: V
authors.lastname: Gudnason
authors.affiliation: Laboratory of Epidemiology and Population Science, National Institute on Aging, Bethesda, Maryland.
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
authors.affiliation: Laboratory of Epidemiology and Population Science, National Institute on Aging, Bethesda, Maryland.
authors.forename: Lenore J
authors.initials: LJ
authors.lastname: Launer
authors.affiliation: Icelandic Gerongological Research Center, National University Hospital of Iceland, Reykjavik. Faculty of Medicine, University of Iceland, Reykjavik.
authors.forename: Palmi V
authors.initials: PV
authors.lastname: Jonsson
mesh_terms: D000367:Age Factors; D000368:Aged; D003863:Depression / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D059647:Gene-Environment Interaction; D015577:Geriatric Assessment; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors
keywords: Aging; Cognitive function.; Depressive symptomatology; Mid-life physical activity