Quasi-causal associations of physical activity and neighborhood walkability with body mass index: A twin study

OBJECTIVE: Physical activity, neighborhood walkability, and body mass index (BMI, kg/m(2)) associations were tested using quasi-experimental twin methods. We hypothesized that physical activity and walkability were independently associated with BMI within twin pairs, controlling for genetic and environmental background shared between them. METHODS: Data were from 6,376 (64% female; 58% identical) same-sex pairs, University of Washington Twin Registry, 2008–2013. Neighborhood walking, moderate-to-vigorous physical activity (MVPA), and BMI were self-reported. Residential address was used to calculate walkability. Phenotypic (non-genetically informed) and biometric (genetically informed) regression was employed, controlling for age, sex, and race. RESULTS: Walking and MVPA were associated with BMI in phenotypic analyses; associations were attenuated but significant in biometric analyses (Ps < 0.05). Walkability was not associated with BMI, however, was associated with walking (but not MVPA) in both phenotypic and biometric analyses (Ps < 0.05), with no attenuation accounting for shared genetic and environmental background. CONCLUSIONS: The association between activity and BMI is largely due to shared genetic and environmental factors, but a significant causal relationship remains accounting for shared background. Although walkability is not associated with BMI, it is associated with neighborhood walking (but not MVPA) accounting for shared background, suggesting a causal relationship between them

Single-Family Housing Value Resilience of Walkable Versus Unwalkable Neighborhoods During a Market Downturn: Causal Evidence and Policy Implications

Objectives: This study investigated the resilience of single-family housing values in walkable versus unwalkable neighborhoods during the economic downturn from 2008 to 2012 in Dallas, Texas. Methods: Using propensity score matching and difference in differences methods, this study established a natural experimental design to compare before-and-after value changes of single-family (SF) homes in walkable neighborhoods with unwalkable neighborhoods during the Great Recession. Two thousand seven hundred ninety-nine SF homes within 18 Tax Increment Financing (TIF) districts were categorized into walkable (Walk Score ≥50) and unwalkable (\u3c50) groups. Six hundred twenty-four dwellings in walkable neighborhoods were matched with the most identical ones in the unwalkable neighborhoods by controlling for the selected structural and residential location variables. Relative average treatment effects were examined for SF values in walkable and unwalkable neighborhoods. Results: On average, the SF homes in walkable neighborhoods held $4566 (2.08%) more value than their how walkable counterparts. Conclusions: This study aims to help planners and decision-makers by documenting the unmet demand for walkable communities and their sustained economic benefit. Increased awareness of the sustained value of walkable communities can be used by lenders who finance and by policy makers who regulate placemaking. Results from this study can be integrated with research that demonstrates health-care cost savings of walkable environments to create an even more comprehensive set of evidence-based interventions to increase their supply