Tomita Andrew, Vandormael Alain M, Cuadros Diego, Di Minin Enrico, Heikinheimo Vuokko, Tanser Frank, Slotow Rob, Burns Jonathan K
College of Health Sciences (A Tomita PhD, A M Vandormael PhD), Africa Health Research Institute (A Tomita, A M Vandormael, Prof F Tanser PhD), School of Life Sciences (E Di Minin PhD, Prof R Slotow PhD), School of Nursing and Public Health (Prof F Tanser), and Department of Psychiatry (Prof J K Burns PhD), University of KwaZulu-Natal, Durban, South Africa; Department of Geography, University of Cincinnati, Cincinnati, OH, USA (D Cuadros PhD); Department of Geosciences and Geography, University of Helsinki, Helsinki, Finland (E Di Minin, V Heikinheimo MSc); Department of Genetics, Evolution and Environment, University College London, London, UK (Prof R Slotow); and Institute for Health Research, University of Exeter, Exeter, UK (Prof J K Burns).
Lancet Planet Health. 2017 Jul;1(4):e152-e162. doi: 10.1016/S2542-5196(17)30063-3.
Unprecedented levels of habitat transformation and rapid urbanisation are changing the way individuals interrelate with the natural environment in developing countries with high economic disparities. Although the potential benefit of green environments for mental health has been recognised, population-level evidence to this effect is scarce. We investigated the effect of green living environment in potentially countering incident depression in a nationally representative survey in South Africa.
We used panel data from the South African National Income Dynamics Study (SA-NIDS). Our study used SA-NIDS data from three waves: wave 1 (2008), wave 2 (2010), and wave 3 (2012). Households were sampled on the basis of a stratified two-stage cluster design. In the first stage, 400 primary sampling units were selected for inclusion. In the second stage, two clusters of 12 dwelling units each were drawn from within each primary sampling unit (or 24 dwelling units per unit). Household and individual adult questionnaires were administered to participants. The main outcome, incident depression (ie, incident cohort of 11 156 study participants without significant depression symptoms at their first entry into SA-NIDS), was assessed in the adult survey via a ten item version of the Center for Epidemiologic Studies Depression Scale; a total score of ten or higher was used as a cutoff to indicate significant depressive symptoms. Each participant was assigned a value for green living space via a satellite-derived normalised difference vegetation index (NDVI) based on the GPS coordinates of their household location.
Overall, we found uneven benefit of NDVI on incident depression among our study participants. Although the green living environment showed limited benefit across the study population as a whole, our final analysis based on logistic regression models showed that higher NDVI was a predictor of lower incident depression among middle-income compared with low-income participants (adjusted odds ratio [aOR] 0·98, 0·97-0·99, p<0·0001), although when this analysis was broken down by race, its positive effect was particularly evident amongst African individuals. Living in rural areas was linked to lower odds of incident depression (aOR 0·71, 0·55-0·92, p=0·011) compared with study participants residing in urban informal areas that often lack formal planning.
Our results imply the importance of green environments for mental wellbeing in sub-Saharan African settings experiencing rapid urbanisation, economic and epidemiological transition, reaffirming the need to incorporate environmental services and benefits for sustainable socioeconomic development.
South African Medical Research Council, National Institutes of Health, and Academy of Finland.
前所未有的栖息地转变水平和快速城市化正在改变经济差距巨大的发展中国家个人与自然环境相互关联的方式。尽管绿色环境对心理健康的潜在益处已得到认可，但这方面的人群层面证据却很匮乏。我们在南非一项具有全国代表性的调查中，研究了绿色生活环境对预防新发抑郁症的影响。
我们使用了南非国民收入动态研究（SA-NIDS）的面板数据。我们的研究使用了SA-NIDS三个波次的数据：第1波（2008年）、第2波（2010年）和第3波（2012年）。家庭抽样采用分层两阶段整群设计。在第一阶段，选择400个初级抽样单位纳入。在第二阶段，从每个初级抽样单位中抽取两个群，每个群有12个居住单元（即每个单位24个居住单元）。对参与者进行家庭和个人成人问卷调查。主要结局，即新发抑郁症（即11156名首次进入SA-NIDS时无明显抑郁症状的研究参与者的新发队列），在成人调查中通过流行病学研究中心抑郁量表的10项版本进行评估；总分10分及以上作为有明显抑郁症状的临界值。根据家庭位置的GPS坐标，通过卫星衍生的归一化植被指数（NDVI）为每个参与者分配一个绿色生活空间值。
总体而言，我们发现NDVI对我们研究参与者的新发抑郁症的益处并不均衡。尽管绿色生活环境对整个研究人群的益处有限，但我们基于逻辑回归模型的最终分析表明，与低收入参与者相比，较高的NDVI是中等收入参与者中较低新发抑郁症的预测因素（调整后的优势比[aOR]为0·98，0·97 - 0·99，p<0·0001），尽管按种族细分该分析时，其积极作用在非洲个体中尤为明显。与居住在通常缺乏正规规划的城市非正式地区的研究参与者相比，生活在农村地区与较低的新发抑郁症几率相关（aOR为0·71，0·55 - 0·92，p = 0·011）。
我们的结果表明，在经历快速城市化、经济和流行病学转变的撒哈拉以南非洲地区，绿色环境对心理健康很重要，重申了将环境服务和益处纳入可持续社会经济发展的必要性。
南非医学研究理事会、美国国立卫生研究院和芬兰科学院。
