Exposure to natural settings has been linked with a vast array of human health benefits, from reduced rates of depression to increased immune functioning. Two recent studies found evidence suggesting that urban green spaces, such as parks and gardens, may also improve cognitive development and buffer against the effects of health inequality.

In research reported last year in the Proceedings of the National Academy of Sciences USA, investigators in Spain, Norway and the U.S. explored the cognitive development of 2,593 children between the ages of seven and 10 from 36 primary schools in Barcelona. At regular intervals over a period of 12 months, they tracked changes in memory and attentiveness using cognitive tests, and they used high-resolution satellite data to assess the children's proximity to green space at home and school and during their commute. After factoring out socioeconomic status and other potential confounders, they determined that children who were closer to parkland had better memory development and less inattentiveness than other children.

The study authors suggest that green spaces may have a positive effect both directly and indirectly. “Green spaces provide children with opportunities to develop mental skills such as discovery and creativity,” says co-author Payam Dadvand, a physician and researcher at the Center for Research in Environmental Epidemiology in Barcelona. More indirectly, green spaces may help by reducing exposure to air pollution and noise, increasing physical activity, and enriching microbial input from the environment, all of which have been associated with improved mental development, he says. When the researchers measured and factored in traffic-related air pollution, which is higher in places with fewer plants and trees, they found that it accounted for 20 to 65 percent of the observed association between greenness and cognitive development. Air pollution has been shown to have neurotoxic effects, Dadvand says.

Natural settings may also help reduce the mental health burden that comes with socioeconomic inequality, according to a paper by researchers at the University of Glasgow and the University of Edinburgh. A cross-sectional observational study published last year in the American Journal of Preventive Medicine sought to determine which neighborhood characteristics might be “equigenic,” or capable of disrupting the relation between socioeconomic disparities and health inequality. Using data from 21,294 adults living in urban areas in 34 European countries, the scientists examined associations between participants' level of financial stress and psychological well-being. Then they explored interactions between those variables and five neighborhood characteristics or services, including access to green spaces, banking and postal services, public transportation and cultural facilities. Results show that the difference in well-being scores among people experiencing the most and least financial difficulty diminished with greater access to green spaces, such that the health gap was 40 percent smaller among those with better access. No such benefits were found with any of the other variables studied.

Approximately half of the world's current population lives in urban areas, and that number is expected to increase, Dadvand says. Findings such as these could influence policy makers to increase access to green spaces, in the hopes that doing so might boost mental health in nearby residents and improve academic achievement in children. “That could have long-term consequences for individuals, families and society as a whole,” Dadvand says.