Greening vacant properties as a cost-effective mental health intervention in underserved populations

Relation

South EC, Hohl BC, Kondo MC, MacDonlad JM, Branas CC. Effect of greening vacant land on mental health: a city-wide randomized controlled trial.JAMA network opened. 2018;1 (under review):1–14.

Study objective

To assess whether greening undeveloped urban land reduces self-reported poor mental health among community-dwelling adults

Draft

This study included 541 vacant urban lots in Philadelphia based on meeting the criteria for "blight": unkempt vegetation, trash, abandoned cars, etc. These lots were selected from a larger "clean and green" urban renewal project led by the Philadelphia Horticultural Society.¹Lots were grouped into 110 proximity clusters with radii of 0.25 to 0.50 miles and randomly assigned to 1 of 3 intervention groups:

• Müllabfuhr: Alle sichtbaren Abfälle und weggeworfenen Gegenstände wurden vom Grundstück entfernt, überwucherte Vegetation wurde getrimmt/gemäht und monatliche Wartungsarbeiten wurden durchgeführt.
• Begrünung: Zusätzlich zu den oben genannten Aktivitäten wurden die Grundstücke in dieser Gruppe professionell eingeebnet, Rasenflächen und kleine Bäume gepflanzt und kurze Zäune um die Grundstücksgrenzen herum installiert.
• Kontrolle: An diesen Chargen wurde während der Dauer der Studie kein Eingriff durchgeführt. (Nach Abschluss der Studie wurden diese Grundstücke auch begrünt).

Participant

Urban residents living on one of the property clusters (N = 342) completed this study, which consisted of completing a survey focused on perceptions of “urban health.” This survey was conducted before the procedure and again ~18 months later after the litter removal/greening had occurred. Participants and data collectors were blinded to the intervention (i.e., survey data collection was conducted independently of knowledge that the intervention took place on local vacant lots). Participants had a mean age of 44.6 years (SD 15.1 years), were 60% female, and 44% had a below-poverty household income of $19,530.

Target parameters

As part of a larger survey, participants completed the self-report Kessler-6 Psychological Distress Scale (K6) before and after the greening/cleaning/control initiative. This scale measures the frequency of recent subjective experiences of nervousness, hopelessness, restlessness, depression, worthlessness, and strain. A pairwise comparison of pre-post changes was performed between intervention groups using intention-to-treat cross-sectional time series regression.

Key insights

Reductions in K6 scales occurred in all groups during the 18 months of the intervention, possibly reflecting changes in the national economy during the study period (2011-2013, the recovery period following the Great Recession).

Independent of these baseline changes, there were significant reductions in self-reported feelings of depression and worthlessness among residents living in the greening clusters compared to the control clusters. Depression was reduced by 42% (95% CI: -63.6% to -5.9%;P=0.03) and worthlessness decreased by 51% (95% CI: -74.7% to -4.7%;P=0.04), compared to no significant reduction in the control clusters. There was also a trend in reduction in the K6 composite score (i.e., overall self-reported poor mental health) of 63% (95% CI: −86.2% to 0.4%;P= 0.051) compared to the control.

For residents living in households below the poverty line in the greening clusters, the reduction in depression was even greater (68.7%) compared to residents in the control cluster (95% CI: −86.5% to −27.5%;P=0.007).

There was no statistical difference between garbage disposal and control cluster residents in either K6 total scores or subscale scores.

Practice implications

This is one of the first studies to use an experimental design (i.e., random assignment to variable vs. control conditions) for the urban green space approach to promoting public health. Unlike previous studies in this area, the current study is able to attribute direct causation of mental health benefits to greening vs. control conditions. This very important step allows for a direct benefit analysis (including cost-benefit analysis). [CBA]) of the intervention so that they can be replicated, expanded and developed into viable programs in the future. A preliminary CBA analysis of a similar study found a return on investment (ROI) of $224 per dollar invested.²

The results of this study demonstrate the importance of environmental factors in influencing individual and community mental health. These effects have been known for many years, both in clinical and academic contexts and through direct human experience.³Most people are aware of how their environment can influence their mood, ability to concentrate and outlook on life. The stimuli of our environment have a direct impact on neuroendocrine activity and the corresponding affective and cognitive functions.⁴

This may be particularly relevant in modern urban environments, where stimuli can be significantly different and more intense than in a rural landscape to which we are more evolutionarily adapted.⁵The “urban stress” theory suggests that life in cities may be inherently less healthy (evolutionarily speaking) due to these “new” environments. A significant amount of evidence supports this concept.^6.7

This problem is particularly concerning for the underserved urban population (i.e., the urban poor). These populations have some of the worst health conditions in the country due to a variety of factors, including limited access to health care; air, noise and light pollution; Crime; psychosocial stress; and increased allostatic load.⁸In particular, the unique combination of poverty and urban decay has been shown to directly contribute to higher rates of depression in these populations.⁹

It is already known that urban greenery is beneficialphysicallyHealth, especially for the urban poor. In a landmark study published in thelancetThe researchers showed that proximity to urban green space was not only associated with lower mortality (after controlling for socioeconomic status [SES]), but that when groups were stratified by SES, the effect of green space was far more important in lower SES groups than in higher SES groups.¹⁰For people at the bottom of the economic ladder, the “healing power of nature” can be a significant life-saving resource.

Many studies have shown that urban green spaces can have a positive impact on the environmentspirituallythe health. Previous editions of NMJ have reviewed some of these studies.^11,12One approach that has been explored to improve the health of the urban poor is the “urban greening” movement that has emerged across the country. These initiatives combine the salutogenic aspects ofBiophiliathe concept popularized by E.O. Wilson, which suggests that people have an inherent healthy affinity for natural places, with public health programs such as the CDC's now-defunct Healthy Places Initiative.^13,14The Philadelphia Horticultural Society is one of the national leaders in not only pursuing urban greening efforts, but also collecting data to demonstrate the essential benefits and effectiveness of their programs.^15,16By reducing urban blight and improving the local environment, it is possible to change the conditions under which health, including mental health and quality of life, emerges.

A limitation of this study is the lack of data identifying urban residents' direct exposure to the vacant lots before, during, and after the interventions. In the current study, it is not possible to link changes in K6 values ​​to participants' use or appreciation of the revegetated properties. However, the experimental design of the study suggests that an aspect of causality rather than a simple correlation emerged, as noted above. Future studies may wish to add a measure of individual exposure to green spaces as an additional metric for the analysis, but this does not detract from the value or results of the current study.

Conclusions

This study extends the idea of ​​“medicine” beyond the level of personal impact and shows that large-scale public health interventions, particularly those that involve greening the environments in which we live, work, and play, can significantly improve mental health and well-being in a community, particularly for the most vulnerable members of society.