Department of Geography, University of Buffalo, The State University of New York, NY, USA.
Veterans Medical Research Institute, Veterans Health Service Medical Center, Seoul, Republic of Korea.
BMC Public Health. 2024 Sep 19;24(1):2556. doi: 10.1186/s12889-024-19952-2.
A number of studies based on young to middle aged adult and child samples have found that exposure to greenspace and bluespace can have a positive impact on mental health and well-being. However, there is limited research among older adults and the extant studies have provided mixed results. The present study was designed to examine how the association between these forms of exposure and depressive symptoms among older adults varies as a function of different spatially and temporally resolved exposure metrics.
The sample consisted of 617 individuals (46.19% female) aged ≥ 60 years of age. Depressive symptoms were measured using the 10-item Center for Epidemiological Studies Depression Scale (CES-D). Individuals' greenspace exposure was quantified using spatially and temporally resolved metrics, including monthly and annual averaged satellite-derived normalized difference vegetation index (NDVI) across multiple buffer distances (250 m to 2,000 m) centered at participants' home address. We also quantified exposure to blue-greenspace from a highly detailed land use and land cover dataset. A multivariable logistic regression model assessed the association between greenspace and blue-greenspace exposure and depressive symptoms, adjusting for age, sex, income, education, marital status, current smoking, alcohol status, medical conditions, temperature, crime rate, population density, and per capita park area.
We found a significant association between exposures to greenspace and blue-greenspace and depressive symptoms (CES-D cutoff ≥ 4) among older adults. After adjusting for confounding variables, the odds of depressive symptoms were significantly decreased by an IQR increment in residential exposure to greenspace [odds ratio (OR) = 0.67; 95% confidence interval (95% CI), 0.49 ~ 0.91] and blue-greenspace (OR = 0.59; 95% CI, 0.41 ~ 0.84) measured nearby their home address (i.e., as close as 250 m). When stratified by household income level, the association was only significant among low-income individuals. We also found temporal variation in the association between depressive symptoms and monthly NDVI-based greenspace exposure, in which the odds of depressive symptoms were the lowest for greenspace in cold months (i.e., January, February, and March).
Our findings suggest that neighborhood greenspace may serve as a protective factor against depression among older adults, but the benefits may depend on the spatial and temporal context. More investigation is needed to replicate our findings on the spatial and temporal variations of greenspace exposure metrics and their effects on depressive symptoms.
多项基于中青年和儿童样本的研究发现，接触绿地和蓝地（包括自然景观和城市中的水体）对心理健康和幸福感有积极影响。然而，针对老年人的研究有限，现有的研究结果存在差异。本研究旨在探讨在不同的空间和时间分辨率暴露指标下，这些暴露形式与老年人抑郁症状之间的关联如何变化。
该样本由 617 名年龄≥60 岁的个体（46.19%为女性）组成。抑郁症状使用 10 项中心流行病学研究抑郁量表（CES-D）进行测量。个体的绿地暴露量使用空间和时间分辨率指标进行量化，包括以参与者家庭住址为中心的多个缓冲区距离（250 米至 2000 米）的每月和年度平均卫星衍生归一化差异植被指数（NDVI）。我们还从高度详细的土地利用和土地覆盖数据集量化了蓝绿空间的暴露情况。多变量逻辑回归模型评估了绿地和蓝绿空间暴露与抑郁症状之间的关联，调整了年龄、性别、收入、教育、婚姻状况、当前吸烟状况、饮酒状况、身体状况、温度、犯罪率、人口密度和人均公园面积等混杂变量。
我们发现，老年人的绿地和蓝绿空间暴露与抑郁症状（CES-D 得分≥4）之间存在显著关联。在调整混杂变量后，住宅绿地暴露每增加一个 IQR，抑郁症状的几率显著降低[优势比（OR）=0.67；95%置信区间（95%CI），0.490.91]，住宅附近的蓝绿空间暴露（OR=0.59；95%CI，0.410.84）也是如此。按家庭收入水平分层后，这种关联仅在低收入个体中显著。我们还发现，抑郁症状与基于每月 NDVI 的绿地暴露之间的关联存在时间变化，在寒冷月份（即 1 月、2 月和 3 月），绿地暴露的抑郁症状几率最低。
我们的研究结果表明，邻里绿地可能是老年人预防抑郁的保护因素，但这种益处可能取决于空间和时间背景。需要进一步研究以复制我们关于绿地暴露指标的空间和时间变化及其对抑郁症状影响的研究结果。
