Department of Human Geography and Spatial Planning, Utrecht University, Netherlands.
Department of Methodology and Statistics, Utrecht University, Netherlands.
Environ Res. 2019 Oct;177:108606. doi: 10.1016/j.envres.2019.108606. Epub 2019 Jul 24.
Research suggests that exposure to the natural environment can improve mood, however, current reviews are limited in scope and there is little understanding of moderators.
To conduct a comprehensive systematic review and meta-analysis of the evidence for the effect of short-term exposure to the natural environment on depressive mood.
Five databases were systematically searched for relevant studies published up to March 2018. Risk of bias was evaluated using the Cochrane Risk of Bias (ROB) tool 1.0 and the Risk of Bias in Non-Randomised Studies of Interventions (ROBINS-I) tool where appropriate. The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach was used to assess the quality of evidence overall. A random-effects meta-analysis was performed. 20 potential moderators of the effect size were coded and the machine learning-based MetaForest algorithm was used to identify relevant moderators. These were then entered into a meta-regression.
33 studies met the inclusion criteria. Effect sizes ranged from -2.30 to 0.84, with an unweighted mean effect size of M=-0.29,SD=0.60. However, there was significant residual heterogeneity between studies and risk of bias was high. Type of natural environment, type of built environment, gender mix of the sample, and region of study origin, among others, were identified as relevant moderators but were not significant when entered in a meta-regression. The quality of evidence was rated very low to low. An assessment of publication bias was inconclusive.
A small effect was found for reduction in depressive mood following exposure to the natural environment. However, the high risk of bias and low quality of studies limits confidence in the results. The variation in effect size also remains largely unexplained. It is recommended that future studies make use of reporting guidelines and aim to reduce the potential for bias where possible.
研究表明，接触自然环境可以改善情绪，但目前的综述范围有限，对调节因素知之甚少。
对短期暴露于自然环境对抑郁情绪的影响进行全面的系统评价和荟萃分析。
系统检索了截至 2018 年 3 月发表的相关研究的五个数据库。使用 Cochrane 偏倚风险（ROB）工具 1.0 和适当的干预措施非随机研究偏倚风险（ROBINS-I）工具评估偏倚风险。使用推荐、评估、发展和评估（GRADE）方法对整体证据质量进行评估。进行了随机效应荟萃分析。对 20 个潜在的效应大小调节因素进行编码，并使用基于机器学习的 MetaForest 算法来识别相关的调节因素。然后将这些因素输入到荟萃回归中。
33 项研究符合纳入标准。效应大小范围从-2.30 到 0.84，未加权平均效应大小 M=-0.29，SD=0.60。然而，研究之间存在显著的剩余异质性，且偏倚风险较高。自然环境类型、建筑环境类型、样本的性别构成以及研究地点等被确定为相关的调节因素，但在荟萃回归中并不显著。证据质量被评为极低至低。对发表偏倚的评估没有定论。
暴露于自然环境后，抑郁情绪有轻微改善。然而，高偏倚风险和低质量研究限制了对结果的信心。效应大小的变化也在很大程度上仍未得到解释。建议未来的研究使用报告指南，并尽可能减少潜在的偏倚。
