title: Are computer and cell phone use associated with body mass index and overweight? A population study among twin adolescents.
abstract: BACKGROUND
  Overweight in children and adolescents has reached dimensions of a global epidemic during recent years. Simultaneously, information and communication technology use has rapidly increased.
  
  
  METHODS
  A population-based sample of Finnish twins born in 1983-1987 (N = 4098) was assessed by self-report questionnaires at 17 y during 2000-2005. The association of overweight (defined by Cole's BMI-for-age cut-offs) with computer and cell phone use and ownership was analyzed by logistic regression and their association with BMI by linear regression models. The effect of twinship was taken into account by correcting for clustered sampling of families. All models were adjusted for gender, physical exercise, and parents' education and occupational class.
  
  
  RESULTS
  The proportion of adolescents who did not have a computer at home decreased from 18% to 8% from 2000 to 2005. Compared to them, having a home computer (without an Internet connection) was associated with a higher risk of overweight (odds ratio 2.3, 95% CI 1.4 to 3.8) and BMI (beta coefficient 0.57, 95% CI 0.15 to 0.98). However, having a computer with an Internet connection was not associated with weight status. Belonging to the highest quintile (OR 1.8 95% CI 1.2 to 2.8) and second-highest quintile (OR 1.6 95% CI 1.1 to 2.4) of weekly computer use was positively associated with overweight. The proportion of adolescents without a personal cell phone decreased from 12% to 1% across 2000 to 2005. There was a positive linear trend of increasing monthly phone bill with BMI (beta 0.18, 95% CI 0.06 to 0.30), but the association of a cell phone bill with overweight was very weak.
  
  
  CONCLUSIONS
  Time spent using a home computer was associated with an increased risk of overweight. Cell phone use correlated weakly with BMI. Increasing use of information and communication technology may be related to the obesity epidemic among adolescents.
authors.affiliation: Dept of Public Health, University of Helsinki, Helsinki, Finland. hanna-reetta.lajunen@helsinki.fi
authors.forename: Hanna-Reetta
authors.initials: HR
authors.lastname: Lajunen
authors.forename: Anna
authors.initials: A
authors.lastname: Keski-Rahkonen
authors.forename: Lea
authors.initials: L
authors.lastname: Pulkkinen
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Rose
authors.forename: Aila
authors.initials: A
authors.lastname: Rissanen
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D040421:Cell Phone / Q000706:statistics & numerical data*; D003201:Computers / Q000706:statistics & numerical data*; D005260:Female; D005387:Finland / Q000453:epidemiology; D015438:Health Behavior; D006801:Humans; D020407:Internet / Q000706:statistics & numerical data*; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000503:physiopathology; D050177:Overweight / Q000502:physiology*; D010067:Ownership / Q000706:statistics & numerical data; D018570:Risk Assessment; D012307:Risk Factors