title: Neighborhood greenness and 2-year changes in body mass index of children and youth.
abstract: BACKGROUND
  Available studies of the built environment and the BMI of children and youth suggest a contemporaneous association with neighborhood greenness in neighborhoods with high population density. The current study tests whether greenness and residential density are independently associated with 2-year changes in the BMI of children and youth.
  
  
  METHODS
  The sample included children and youth aged 3-16 years who lived at the same address for 24 consecutive months and received well-child care from a Marion County IN clinic network within the years 1996-2002 (n=3831). Multiple linear regression was used to examine associations among age- and gender-specific BMI z-scores in Year 2, residential density, and a satellite-derived measure of greenness, controlling for baseline BMI z-scores and other covariates. Logistic regression was used to model associations between an indicator of BMI z-score increase from baseline to Time 2 and the above-mentioned predictors.
  
  
  RESULTS
  Higher greenness was significantly associated with lower BMI z-scores at Time 2 regardless of residential density characteristics. Higher residential density was not associated with Time 2 BMI z-scores in models regardless of greenness. Higher greenness was also associated with lower odds of children's and youth's increasing their BMI z-scores over 2 years (OR=0.87; 95% CI=0.79, 0.97).
  
  
  CONCLUSIONS
  Greenness may present a target for environmental approaches to preventing child obesity. Children and youth living in greener neighborhoods had lower BMI z-scores at Time 2, presumably due to increased physical activity or time spent outdoors. Conceptualizations of walkability from adult studies, based solely on residential density, may not be relevant to children and youth in urban environments.
authors.affiliation: Department of Health Services, School of Public Health and Community Medicine, University of Washington, Seattle, Washington 98195-7230, USA. jfbell@u.washington.edu
authors.forename: Janice F
authors.initials: JF
authors.lastname: Bell
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Wilson
authors.forename: Gilbert C
authors.initials: GC
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D004779:Environment Design; D015444:Exercise; D005260:Female; D006801:Humans; D007196:Indiana / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D009765:Obesity / Q000453:epidemiology*; D010944:Plants; D012111:Residence Characteristics; D012189:Retrospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors