title: The association between smoking and depression from adolescence to adulthood.
abstract: OBJECTIVE
  The association between depression and smoking is firmly established, but how the association develops remains unclear. The aim of this study was to examine development of the smoking-depression association from early adolescence to adulthood.
  
  
  METHODS
  Cross-sectional and longitudinal analyses of the smoking-depression association from adolescence to adulthood.
  
  
  METHODS
  Hordaland, Norway.
  
  
  METHODS
  A cohort of adolescents (initially, 924 pupils) in the Norwegian Longitudinal Health Behaviour Study (NLHB) was followed over nine data collection waves from ages 13 to 30 years.
  
  
  METHODS
  Daily smoking and depressed mood were measured in each wave.
  
  
  RESULTS
  In the cross-sectional analyses, daily smoking and depression were significantly associated (P-value range from P < 0.01 to 0.04) in eight of nine waves. In the final longitudinal model, after controlling for the time-invariant effects of smoking and depression and of tertiary factors, the only significant paths were early adolescent smoking prediction of early adolescent depression (waves 1-2: β = 0.07, P < 0.05; waves 2-3: β = 0.12, P < 0.05) and vice versa (waves 1-2: β = 0.10, P < 0.05; waves 2-3: β = 0.08, P < 0.05).
  
  
  CONCLUSIONS
  The inter-relationship between depression and smoking seems to be due to the reciprocal causal effects between smoking and depression that are established in early adolescence and maintained into adulthood.
authors.affiliation: Uni Health, Bergen, Norway; Department of Health Promotion and Development, Faculty of Psychology, University of Bergen, Bergen, Norway.
authors.forename: Tore
authors.initials: T
authors.lastname: Tjora
authors.forename: Jørn
authors.initials: J
authors.lastname: Hetland
authors.forename: Leif Edvard
authors.initials: LE
authors.lastname: Aarø
authors.forename: Bente
authors.initials: B
authors.lastname: Wold
authors.forename: Nora
authors.initials: N
authors.lastname: Wiium
authors.forename: Simon
authors.initials: S
authors.lastname: Øverland
mesh_terms: D000293:Adolescent; D000328:Adult; D003866:Depressive Disorder / Q000453:epidemiology* / Q000523:psychology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009664:Norway; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology*; D013223:Statistics as Topic; D055815:Young Adult
keywords: Adolescence; adulthood; depression; longitudinal; smoking.