title: Exercise and depressive symptoms in adolescents: a longitudinal cohort study.
abstract: OBJECTIVE
  Physical activity (PA) may have a positive effect on depressed mood. However, whether it can act as a protective factor against developing depressive symptoms in adolescence is largely unknown.
  
  
  OBJECTIVE
  To investigate the association between objectively measured PA and depressive symptoms during 3 years of adolescence.
  
  
  METHODS
  We performed a longitudinal study between November 1, 2005, and January 31, 2010, of a community-based sample from Cambridgeshire and Suffolk, United Kingdom, that included 736 participants (mean [SD] age, 14.5 years [6 months]). The follow-up period was approximately 3 years after baseline (the ROOTS study). Linear regression models were fitted using physical activity energy expenditure (PAEE) and moderate and vigorous physical activity (MVPA) as the predictors and depressive symptoms as the outcome variable. Binomial logistic regression models were also fitted using PAEE and MVPA as the predictors and clinical depression as the outcome measure.
  
  
  METHODS
  Exercise.
  
  
  METHODS
  Individually calibrated heart rate and movement sensing were used to measure PA at baseline only. Physical activity summary measures included total PAEE and time spent in MVPA. These measures were divided into weekend and weekday activity. All participants also completed the Mood and Feelings Questionnaire, a self-report measure of current depressive symptoms, and took part in a Schedule for Affective Disorders and Schizophrenia for School-Age Children-Present and Lifetime Version interview at baseline and 3 years later.
  
  
  RESULTS
  Depressive symptoms at 3-year follow-up were not significantly predicted by any of the 4 PA measures at baseline: weekend MVPA (unstandardized β = 0.02; 95% CI, -0.15 to 0.20; P = .79), weekday MVPA (β = 0.00; 95% CI, -0.17 to 0.17; P = .99), weekend PAEE (β = 0.03; 95% CI, -0.14 to 0.20; P = .75), and weekday PAEE (β = -0.03; 95% CI, -0.20 to 0.14; P = .71). This was also true for major depressive disorder diagnoses at follow-up: weekend MVPA (odds ratio [OR], 1.37; 95% CI, 0.76-2.48; P = .30), weekday MVPA (OR, 1.33; 95% CI, 0.74-2.37; P = .34), weekend PAEE (OR, 1.19; 95% CI, 0.67-2.10; P = .56), and weekday PAEE (OR, 0.92; 95% CI, 0.52-1.63; P = .78).
  
  
  CONCLUSIONS
  No longitudinal association between objectively measured PA and the development of depressive symptoms was observed in this large population-based sample. These results do not support the hypothesis that PA protects against developing depressive symptoms in adolescence.
authors.affiliation: Development and Lifecourse Research Group, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Umar
authors.initials: U
authors.lastname: Toseeb
authors.affiliation: Medical Research Council Epidemiology Unit and UK Clinical Research Collaboration Centre for Diet and Activity Research, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Soren
authors.initials: S
authors.lastname: Brage
authors.affiliation: Medical Research Council Epidemiology Unit and UK Clinical Research Collaboration Centre for Diet and Activity Research, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Corder
authors.affiliation: Development and Lifecourse Research Group, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Valerie J
authors.initials: VJ
authors.lastname: Dunn
authors.affiliation: Development and Lifecourse Research Group, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jones
authors.affiliation: Development and Lifecourse Research Group, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Matthew
authors.initials: M
authors.lastname: Owens
authors.affiliation: Development and Lifecourse Research Group, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: St Clair
authors.affiliation: Medical Research Council Epidemiology Unit and UK Clinical Research Collaboration Centre for Diet and Activity Research, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Esther M F
authors.initials: EM
authors.lastname: van Sluijs
authors.affiliation: Development and Lifecourse Research Group, Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Goodyer
mesh_terms: D000293:Adolescent; D003863:Depression / Q000453:epidemiology* / Q000523:psychology; D003865:Major Depressive Disorder / Q000453:epidemiology* / Q000523:psychology; D004739:England / Q000453:epidemiology; D015444:Exercise / Q000502:physiology* / Q000523:psychology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D011795:Surveys and Questionnaires