Green spaces, subjective health and depressed affect in middle-aged and older adults: a cross-country comparison of four European cohorts

Background Studies on associations between urban green space and mental health have yielded mixed results. This study examines associations of green space exposures with subjective health and depressed affect of middle-aged and older adults in four European cohorts. Methods Data came from four Western-European and Central-European ageing cohorts harmonised as part of the Mindmap project, comprising 16 189 adults with an average age of 50–71 years. Green space exposure was based on the distance to the nearest green space and the amount of green space within 800 m buffers around residential addresses. Cohort-specific and one-step individual participant data (IPD) meta-analyses were used to examine associations of green space exposures with subjective health and depressed affect. Results The amount of green spaces within 800 m buffers was lowest for Residential Environment and CORonary heart Disease (Paris, 15.0 hectares) and highest for Health, Alcohol and Psychosocial factors In Eastern Europe (Czech Republic, 35.9 hectares). IPD analyses indicated no evidence of an association between the distance to the nearest green space and depressed affect (OR 0.98, 95% CI 0.96 to 1.00) or good self-rated health (OR 1.01, 95% CI 0.99 to 1.02). Likewise, the amount of green space within 800 m buffers did not predict depressed affect (OR 0.98, 95% CI 0.96 to 1.00) or good self-rated health (OR 1.01, 95% CI 0.99 to 1.02). Findings were consistent across all cohorts. Conclusions Data from four European ageing cohorts provide no support for the hypothesis that green space exposure is associated with subjective health or depressed affect. While longitudinal evidence is required, these findings suggest that green space may be less important for older urban residents.

Dichotomous indicator of self-assessed health of the participant, indicating good versus less than good health. Based on a score between 0 (terrible) and 10 (excellent) selfrated health, with all scores >7 labeled as good.
Dichotomous indicator of self-assessed health of the participant, indicating good versus less than good health. Based on an original categorization of very good, good, average, poor and very poor self-rated health.

Feels sad, downhearted, or blue
Based on a 4-point ('rarely or none of the time', 'some or a little of the time', 'occasionally or a moderate amount of time', 'most or all of the time') item response to "I felt sad" from the CES-D scale, 20-item version. Participants who responded 'occasionally or a moderate amount of time' or 'most or all of the time' were defined as feeling sad, downhearted or blue.
Based on a 6-point ('all of the time', 'most of the time', 'a good bit of the time', 'some of the time', 'a little of the time', 'none of the time') item response to "How much of the time during the past 4 weeks, have you felt downhearted and blue?" from the MHI-5 scale. Participants who responded 'all of the time' to 'a good bit of the time' were defined as feeling sad, downhearted or blue.
Based on a yes/no item response to "I feel sad at present" from the QD2A depression scale.

Probable caseness of depression
Participants with CESD-20 scores of 16 or higher (out of a possible 60) were defined as cases as per the scale-specific threshold [1].
n.a. Participants with QD2A depression scores of 7 or higher (out of a possible 13) were defined as cases as per the scale-specific threshold [2].
Participants with CESD-20 scores of 16 or higher (out of a possible 60) were defined as cases as per the scale-specific threshold [1].

Probable caseness of psychological distress
The MHI-2 scores (2-12) in LASA were transformed to a scale ranging from 0 to 100. As there is no established cut-off score for the MHI-2, participants whose scores ranged from 50 to 100 were classified as cases.
The MHI-4 scores (4-24) in GLOBE were transformed to a scale ranging from 0 to 100. As there is no established cut-off score for the MHI-4, participants whose scores ranged from 50 to 100 were classified as cases.

MORE DETAILS ON THE GREEN SPACE EXPOSURE MEASURES
The Urban Atlas service offers a high-resolution land use map of urban areas in the European Union. It contains data derived from Earth Observation (EO) data backed by other reference data, such as Commercial Off-The-Shelf (COTS) or Open Street Map (OSM) navigation data and topographic maps [7]. Polygons of specific land use classes need to have a minimal size to be included in a certain category. This size is known as the Minimal Mapping Unit (MinMU). Included in the total green space category are:

GREEN URBAN AREAS
MinMU 0.25 ha, Minimum width: 10 m • Public green areas for predominantly recreational use such as gardens, zoos, parks, castle parks.
• Suburban natural areas that have become and are managed as urban parks.
• Forests or green areas extending from the surroundings into urban areas are mapped as green urban areas when at least two sides are bordered by urban areas and structures, and traces of recreational use are visible.
Not included are: • Private gardens within housing areas; • Cemeteries; • Buildings within parks, such as castles or museums; • Patches of natural vegetation or agricultural areas enclosed by built-up areas without being managed as green urban areas.

MinMU 1 ha
• With ground coverage of tree canopy > 30%, tree height > 5 m, including bushes and shrubs at the fringe of the forest; • Included are plantations such as Populus plantations, Christmas tree plantations; • Forest regeneration / re-colonisation: clear cuts, new forest plantations.
Not included are: • Forests within urban areas and/or subject to high human pressure (see green urban areas).
More details on the land use classification used in the Urban Atlas can be found in the official mapping guide: https://land.copernicus.eu/user-corner/technical-library/urban-atlas-mappingguide-2006