Green Spaces Tied to Fewer Mental Health Hospitalizations – Medscape

Report on Green Space Exposure and its Contribution to Sustainable Development Goals

Executive Summary: Advancing SDG 3 and SDG 11 through Urban Greening

A multinational time series analysis reveals a significant association between exposure to green spaces and a reduced risk of hospital admissions for mental health disorders. These findings provide critical evidence supporting the implementation of policies aligned with Sustainable Development Goal 3 (Good Health and Well-being) and Sustainable Development Goal 11 (Sustainable Cities and Communities). The study demonstrates that increasing vegetation in urban areas is a viable strategy to improve public mental health, reduce healthcare system strain, and build more resilient, sustainable communities.

Methodology and Scope

Data and Population

The analysis incorporated a substantial dataset, reflecting its global relevance:

• Sample Size: 11.4 million hospital admissions for mental disorders.
• Timeframe: Data collected from 2000 to 2019.
• Geographic Scope: Seven countries, including Australia, Brazil, Chile, New Zealand, Thailand, South Korea, and Canada.
• Diagnoses Analyzed:
  1. Psychotic disorders (31%)
  2. Substance use disorders (25%)
  3. Mood disorders (12%)
  4. Behavioral disorders (7%)
  5. Dementia (3%)
  6. Anxiety (2.5%)

Measurement of Greenness

Green space exposure was quantified using the Normalized Difference Vegetation Index (NDVI), a standardized measure indicating vegetation density. This metric allowed for a consistent comparison across diverse geographical regions, linking environmental quality directly to health outcomes.

Key Findings: Evidence for Meeting Sustainable Development Goals

Impact on SDG 3: Good Health and Well-being

The study provides strong quantitative evidence for the positive impact of green spaces on mental health, directly supporting SDG Target 3.4, which aims to promote mental health and well-being.

• A 0.1-unit increase in the NDVI was associated with a 7% lower risk for hospital admissions for all-cause mental disorders.
• The protective associations were strongest for specific, high-burden conditions:
  • Substance use disorders (9% lower risk)
  • Psychotic disorders (7% lower risk)
  • Dementia (6% lower risk)
  • Anxiety (3% lower risk)

Impact on SDG 11: Sustainable Cities and Communities

The findings are particularly relevant for urban planning and achieving SDG Target 11.7, which calls for universal access to safe, inclusive, and accessible green and public spaces.

• In urban settings, greenness was linked to a 13% reduced risk for hospital admissions for all-cause mental disorders.
• An estimated 8000 hospital admissions annually were identified as potentially preventable through increased exposure to green spaces, highlighting a clear pathway for urban interventions to yield significant public health benefits.

Global and Regional Implications

The annual number of potentially preventable hospital admissions associated with greenness exposure varied by country, demonstrating the global applicability of greening strategies:

• Brazil: 4677
• New Zealand: 1213
• Canada: 719
• Thailand: 605
• Chile: 328
• Australia: 150
• South Korea: 20

Policy Recommendations and Broader Impacts

Achieving Health and Economic Co-benefits

The investigators concluded that a significant portion of hospital admissions for mental disorders could be reduced through realistic greening interventions. This approach not only advances health-related SDGs but also generates wider socio-economic advantages consistent with SDG 8 (Decent Work and Economic Growth) and SDG 10 (Reduced Inequalities).

• Reduced healthcare costs and less strain on health systems.
• Improved workplace productivity.
• Enhanced overall community well-being and social cohesion.

Study Considerations

Limitations

The report acknowledges several limitations that should be considered when interpreting the results:

• Data sourced from multiple countries may introduce uncertainties due to differing mental health system management.
• The analysis was limited to severe mental health conditions requiring inpatient care, excluding milder or untreated cases.
• The NDVI metric does not capture qualitative aspects of green spaces, such as accessibility, safety, or biodiversity, which are also crucial for achieving SDG 11.

Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 3: Good Health and Well-being

  The article directly addresses this goal by investigating the link between exposure to green spaces and mental health outcomes. It highlights that higher levels of “greenness” are associated with a “decreased risk for hospital admissions for mental health disorders,” including substance use disorders, psychotic disorders, dementia, and anxiety. This connects to the promotion of mental health and well-being for all ages.

• SDG 11: Sustainable Cities and Communities

  This goal is relevant as the study emphasizes the importance of green spaces, particularly in urban environments. The article states that the protective association between greenness and mental health is especially strong “in urban areas.” The finding that “nearly 8000 admissions annually were deemed potentially preventable with greater greenness exposure” in urban settings underscores the role of green infrastructure in creating sustainable and healthy cities.

What specific targets under those SDGs can be identified based on the article’s content?

1. SDG 3: Good Health and Well-being

   • Target 3.4: By 2030, reduce by one third premature mortality from non-communicable diseases through prevention and treatment and promote mental health and well-being.

     The article’s core finding that increased greenness is associated with a “7% lower risk for hospital admissions for all-cause mental disorders” directly supports the promotion of mental health and well-being. The study suggests that “greening interventions” could be a preventative measure to reduce the burden of severe mental health conditions requiring hospitalization, thereby contributing to this target.

2. SDG 11: Sustainable Cities and Communities

   • Target 11.7: By 2030, provide universal access to safe, inclusive and accessible, green and public spaces, particularly for women and children, older persons and persons with disabilities.

     The article provides evidence for the benefits of achieving this target. It demonstrates a quantifiable positive impact of green spaces on public health, noting that in urban settings, “greenness was linked to a 13% reduced risk for hospital admissions for all-cause mental disorders.” This reinforces the importance of creating and maintaining green public spaces as a critical component of urban planning for community well-being.

Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

1. Indicators for Target 3.4 (Promote mental health and well-being)

   • Rate of hospital admissions for mental health disorders: The study uses “hospital admissions for mental disorders” as its primary outcome. The article quantifies this with a relative risk (RR) metric, stating a “0.1-unit increase in the vegetation index was associated with a 7% lower risk for hospital admissions” (RR, 0.93). This rate serves as a direct indicator of the burden of severe mental illness.
   • Annual number of preventable hospital admissions: The article explicitly mentions the “annual number of hospital admissions for all-cause mental disorders associated with exposure to greenness,” providing specific figures for countries like New Zealand (1213) and Brazil (4677). This metric can be used to track the potential impact of greening interventions on healthcare systems.

2. Indicators for Target 11.7 (Provide universal access to green spaces)

   • Normalized Difference Vegetation Index (NDVI): The article uses the NDVI to quantify “greenness.” It defines different levels of vegetation based on NDVI values (e.g., “very low values (≤ 0.1) indicating barren areas” and “high values (≥ 0.6) indicating dense vegetation”). This index serves as a direct, measurable indicator of the extent and density of green space in a given area, which is central to Target 11.7.

SDGs, Targets, and Indicators Table

Source: medscape.com