A number of studies have documented associations between environmental characteristics and children's physical activity and body mass index (BMI). The availability of parks or green space, for example, is linked to more desirable activity levels and weight in children. Higher levels of crime and negative perceptions of the neighborhood, on the other hand, are associated with lower levels of physical activity and less healthy weights in children. While studies have documented these associations, the design of the studies prevents drawing conclusions about causality.
The current study, by using a longitudinal design, gets closer to assessing causality. Data for this study was based on BMI assessments of 6001 children in the United Kingdom conducted when they were 3, 5, 7 and 11 years of age. Data relating to the environments in which the children lived was also collected at each time point. This environmental data included level of green space, gardens (yards), and crime or multiple deprivation of a neighborhood.
An initial analysis of the data showed a significant link between the levels of crime and the amount of gardens in the area with children's BMI. Children living in neighborhoods with less crime and more gardens tended to have a significantly lower BMI (healthier weight). There were some differences, however, between boys and girls and between children based on their parent's educational level. More crime was associated with higher BMI for boys; fewer gardens were associated with higher BMI for girls. Both higher crime and fewer gardens were significantly associated with increased child BMI for higher educated parents. Yet, for lower-educated parents or guardians, neither levels of crime nor the amount of gardens seemed to have an effect on child BMI.
Generally, this longitudinal study found that environments with more gardens and lower crime tended to result in slightly lower BMI for children. The findings were not significant enough, however, to support the idea that environmental factors can be a key determinant of changes in childhood overweight/ obesity. In other words, the findings of this study do not establish a causal relationship between environmental characteristic and a child's BMI. “Future studies might benefit from closer attention to selection into neighbourhoods with more or less green space, and revisit assumptions about the ways in which environments independently impact children's activity.”
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