Association between neighborhood walkability and physical activity in a community-based twin sample.

This study examined the associations between neighborhood walkability—measured by the Built Environment and Health Research Group Neighborhood Walkability Index (BEH-NWI), which includes intersection density, population density, and destination accessibility—and physical activity outcomes using a large sample of 5,477 monozygotic and same-sex dizygotic twin pairs from the Washington State Twin Registry. Employing a twin design to control for genetic and shared environmental confounding, the researchers found a robust "quasi-causal" positive association between walkability and neighborhood walking, with a 1% increase in walkability linked to a 0.42% increase in walking minutes per week. In contrast, associations between walkability and moderate-to-vigorous physical activity (MVPA) and transit use were not significant after accounting for familial and demographic factors, although higher walkability was associated with a reduced likelihood of zero transit use. These findings suggest that neighborhood walkability may directly influence walking behavior, while its relationship with broader physical activity and transit use is more strongly affected by familial and demographic confounders.