The Association between Green Space and Adolescents’ Mental Well-Being: A Systematic Review

This systematic review summarised and evaluated the evidence for associations between green space and adolescents’ mental well-being. The PRISMA statement guidelines were followed for reporting systematic reviews. Fourteen articles met the inclusion criteria for this review. Synthesis suggests beneficial associations between green space exposure and reduced stress, positive mood, less depressive symptoms, better emotional well-being, improved mental health and behaviour, and decreased psychological distress in adolescents. Several studies found the relationship varied by demographic and socio-economic factors. The limited number of studies and the risk of bias were the main limitations, together with heterogeneity regarding green space and mental well-being assessments. Overall, this review highlights the potential contribution of green space in schoolyards. Improving the availability, accessibility and quality of green space is likely to generate positive impacts on adolescents’ mental well-being. More consistent evidence on the use of different types of green space and perceptions of features are needed in the future.


Rationale
3 Describe the rationale for the review in the context of what is already known.

P2
Objectives 4 Provide an explicit statement of questions being addressed with reference to participants, interventions, comparisons, outcomes, and study design (PICOS).

METHODS
Protocol and registration 5 Indicate if a review protocol exists, if and where it can be accessed (e.g., Web address), and, if available, provide registration information including registration number.

P2
Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale.

P3
Information sources 7 Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.

P2
Search 8 Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.

P3
Study selection 9 State the process for selecting studies (i.e., screening, eligibility, included in systematic review, and, if applicable, included in the meta-analysis).

P3
Data collection process 10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.

P2-P3
Data items 11 List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made.

P2-P4
Risk of bias in individual studies 12 Describe methods used for assessing risk of bias of individual studies (including specification of whether this was done at the study or outcome level), and how this information is to be used in any data synthesis.

P4
Summary measures 13 State the principal summary measures (e.g., risk ratio, difference in means).

P4
Synthesis of results 14 Describe the methods of handling data and combining results of studies, if done, including measures of consistency (e.g., I 2 ) for each meta-analysis.

P3-P4
Section/topic # Checklist item Reported on page # Risk of bias across studies 15 Specify any assessment of risk of bias that may affect the cumulative evidence (e.g., publication bias, selective reporting within studies).

P3
Additional analyses 16 Describe methods of additional analyses (e.g., sensitivity or subgroup analyses, meta-regression), if done, indicating which were pre-specified.

Study selection
17 Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.

P4
Study characteristics 18 For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.

P4
Risk of bias within studies 19 Present data on risk of bias of each study and, if available, any outcome level assessment (see item 12).

P4. P19
Results of individual studies 20 For all outcomes considered (benefits or harms), present, for each study: (a) simple summary data for each intervention group (b) effect estimates and confidence intervals, ideally with a forest plot.

P5-P18
Synthesis of results 21 Present results of each meta-analysis done, including confidence intervals and measures of consistency.

P5-P18
Risk of bias across studies 22 Present results of any assessment of risk of bias across studies (see Item 15).

DISCUSSION
Summary of evidence 24 Summarize the main findings including the strength of evidence for each main outcome; consider their relevance to key groups (e.g., healthcare providers, users, and policy makers).

P29-32
Limitations 25 Discuss limitations at study and outcome level (e.g., risk of bias), and at review-level (e.g., incomplete retrieval of identified research, reporting bias).  Green space (green space* or greenspace* or greenness or greenery or green area* or greenway* or green belt* or green corridor* or natural environment* or open space* or park or parks or natur* space* or naturalness or garden* or playground or canopy or tree* or forest or forests or woodland* or green roof* or roof garden* or arboretum or urban nature

Green space
Trees/ OR (green adj2 space*).ti,ab,kw. OR (green space* or greenspace* or greenness or greenery or green area* or greenway* or green belt* or green corridor* or natural environment* or open space* or park or parks or natur* space* or naturalness or garden* or playground or canopy or tree* or forest or forests or woodland* or green roof* or roof garden* or arboretum or urban nature).ti,ab,kw.

116
Mental well-being Stress, Psychological/ OR Mental Health/ OR Anxiety/ OR Depression/ OR Happiness/ OR Pleasure/ OR (wellbeing or well being or wellness or emotional health or psychological health or mental health or mood or depress* or anxiety or stress or happiness or pleasure).ti,ab,kw. Adolescent Adolescent/ OR (teen* or adolescen* or youth* or juvenile* or young people or young person or young adult* or high school* or secondary school* or senior school*).ti,ab,kw. EMBASE (Ovid interface) Green space (green adj2 space*).ti,ab,kw. OR recreational park/ OR canopy/ OR "tree"/ OR forest/ OR (green space* or greenspace* or greenness or greenery or green area* or greenway* or green belt* or green corridor* or natural environment* or open space* or park or parks or natur* space* or naturalness or garden* or playground or canopy or tree* or forest or forests or woodland* or green roof* or roof garden* or arboretum or urban nature).ti,ab,kw.

734
Mental well-being wellbeing/ OR mental health/ OR mood/ OR depression/ OR anxiety/ OR happiness/ OR stress/ OR pleasure/ OR (wellbeing or well being or wellness or emotional health or psychological health or mental health or mood or depress* or anxiety or stress or happiness or pleasure).ti,ab,kw. Adolescent adolescent/ OR juvenile/ OR (teen* or adolescen* or youth* or juvenile* or young people or young person or young adult* or high school* or secondary school* or senior school*).ti,ab,kw. PsycINFO (Ovid interface) Green space (green adj2 space*).ti,ab,id OR "Nature (Environment)"/ OR Playgrounds/ OR (green space* or greenspace* or greenness or greenery or green area* or greenway* or green belt* or green corridor* or natural environment* or open space* or park or parks or natur* space* or naturalness or garden* or playground or canopy or tree* or forest or forests or woodland* or green roof* or roof garden* or arboretum or urban nature).ti,ab,id 298 Mental well-being Well Being/ OR Mental Health/ OR Anxiety/ OR Stress/ OR Happiness/ OR Pleasure/ OR (wellbeing or well being or wellness or emotional health or psychological health or mental health or mood or depress* or anxiety or stress or happiness or pleasure).ti,ab,id Adolescent (teen* or adolescen* or youth* or juvenile* or young people or young person or young adult* or high school* or secondary wellness OR "emotional health" OR "psychological health" OR "mental health" OR mood OR depress* OR anxiety OR stress OR happiness OR pleasure ) AND PUBYEAR > 1999 Adolescent TITLE-ABS-KEY ( teen* OR adolescen* OR youth* OR juvenile* OR "young people" OR "young person" OR "young adult*" OR "high school*" OR "secondary school*" OR "senior school*" ) AND PUBYEAR > 1999 GEOBASE Green space found in GEOBASE for 2000-2020: (("green space*" or greenspace* or greenness or greenery or "green area*" or "greenway*" or "green belt*" or "green corridor*" or "natural environment*" or "open space*" or park or parks or "natur* space*" or naturalness or garden* or playground or canopy or tree* or forest or forests or woodland* or "green roof*" or "roof garden*" or arboretum or "urban nature" or "green NEAR/2 space") WN KY) AND (English WN LA)

2136
Mental well-being found in GEOBASE for 2000-2020: ((wellbeing OR "well being" OR wellness OR "emotional health" OR "psychological health" OR "mental health" OR mood OR depress* OR anxiety OR stress OR happiness OR pleasure) WN KY) AND (English WN LA) adolescent found in GEOBASE for 2000-2020: ((teen* or adolescen* or youth* or juvenile* or "young people" or "young person" or "young adult*" or "high school*" or "secondary school*" or "senior school*") WN KY) AND (English WN LA)