(Reuters Health) - Getting rid of trash, planting new grass and trees and making other improvements to vacant lots may reduce neighbors’ feelings of depression and worthlessness, a recent study suggests.

Improving blighted areas could be an inexpensive way for communities to help address local mental health, say the authors.

“As an emergency medicine physician, I see the downstream effects that poverty and neighborhood environment have on health all the time,” study leader Dr. Eugenia South of the University of Pennsylvania in Philadelphia told Reuters Health in an email.

“You can’t escape your environment. It is with you day in and day out. We know it is going to have an impact on both physical and mental health and my goal is to make that impact a positive one,” she said.

Where people live, and specifically the physical environment of their neighborhood, has an impact on their health, said South.

“For people living in areas with dilapidated neighborhood environments, that impact is likely to be negative. Vacant lot greening is a simple and relatively low-cost neighborhood intervention that can turn an unhealthy environment into a healthy one,” she said.

As reported in JAMA Network Open, South and her colleagues randomly assigned 541 vacant lots in Philadelphia to one of three groups: greening intervention, trash cleanup only, or no intervention.

The greening intervention included removing debris, grading the land, planting new grass and a few trees, installing a low wooden perimeter fence with openings, and doing regular maintenance.

In addition, the study team interviewed 342 randomly selected nearby residents about their mental health, twice in the 18 months before the interventions and twice during the 18 months afterward. Nearly 45 percent of participants had annual family incomes of less than $25,000.

The study team found that reports of feeling depressed fell by about 40 percent and reports of feeling worthless were reduced by about 60 percent among people living near greened vacant lots compared with people living near lots that were left alone. The rate of self-reported poor mental health was also lower among those living near greened vacant land, but the difference was too small to be statistically significant.

Simply cleaning up the trash didn’t have much of an effect.

The vacant lot greening intervention, which was created and implemented by the Pennsylvania Horticulture Society, is a simple, low-cost intervention that can be easily implemented and scaled up,” South said.

A commentary published with the study points out that a growing body of evidence ties contact with nature to health benefits.

However, previous studies have not been able to prove that natural spaces can improve mental health, commentary coauthor Michael Jerrett told Reuters Health in a phone call. If people choose to be near those spaces, or if wealthier people are more likely to afford being near them, that makes it harder to prove cause and effect.

Jerrett, a researcher with the Fielding School of Public Health at the University of California, Los Angeles, says the current study was able to “eliminate, or at least greatly minimize, the chance of the self-selection bias influencing the results, so that you’re getting something that’s starting to approximate what you would get in a randomized, controlled trial.”

SOURCE: bit.ly/2mDBS8h and bit.ly/2Mg1uDe, JAMA Network Open, online July 20, 2018.