Neighborhood greenspace exposure as a protective factor in dementia risk among U.S. adults 75 years or older: a cohort study

Abstract

Background Research suggests that greenspace may confer neurocognitive benefits. This study examines whether residential greenspace is associated with risk of dementia among older adults. Methods Greenspace exposure was computed for 3047 participants aged 75 years and older enrolled in the Gingko Evaluation of Memory Study (GEMS) across four U.S. sites that prospectively evaluated dementia and its subtypes, Alzheimer’s disease (AD), vascular dementia (VaD), and mixed pathologies, using neuropsychiatric evaluations between 2000 and 2008. After geocoding participant residences at baseline, three greenspace metrics—Normalized Difference Vegetative Index, percent park overlap within a 2-km radius, and linear distance to nearest park—were combined to create a composite residential greenspace measure categorized into tertiles. Cox proportional hazards models estimated the associations between baseline greenspace and risk of incident all-cause dementia, AD, and Mixed/VaD. Results Compared to low residential greenspace, high residential greenspace was associated with a reduced risk of dementia (HR = 0.76 95% CI: 0.59,0.98) in models adjusted for multiple covariates. After additional adjustment for behavioral characteristics, Apolipoprotein E ɛ4 status, and other covariates, the association was slightly attenuated (HR = 0.82; 95% CI:0.63,1.06). Those exposed to medium levels of greenspace also had 28% lower risk (HR = 0.72; CI: 0.55, 0.95) of dementia compared to those with low greenspace in adjusted models. Subtype associations between high residential greenspace and AD were not statistically significant. Greenspace was not found to be significantly associated with mixed/vascular pathologies. Conclusions This study showed evidence for an association between residential greenspace and all-cause dementia among older adults. Future research with larger sample size, precise characterization of different dementia subtypes, and assessment of residential greenspace earlier in life may help clarify the role between exposure to greenspace and dementia risk.

Is Greenness Associated with Dementia? A Systematic Review and Dose–Response Meta-analysis

“…After their in-depth evaluation, we further excluded two studies because they analyzed the same population [ 61 , 62 ••], 17 studies because they did not evaluate the exposure or outcome of interest (such as the two measuring cognitive decline but not cognitive impairment [ 19 , 40 ]), and six papers because they were not original research articles. Overall, 12 publications eventually met the inclusion criteria, i.e., they had individual-level data and reported the association of greenness with dementia and/or cognitive impairment [ 47 – 50 , 63 – 65 , 66 ••, 67 , 68 ••, 69 , 70 ].

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“…Four studies used the International Classification of Disease, Injuries and Causes of Death (ICD versions 9 and 10) to measure outcome [47,64,68 [48,50,67], though one of them was based on an adapted version of the MMSE [50]. One study used a series of clinical and neuropsychological tests for diagnosis of dementia classified according to DSM-IV criteria [69].…”

The role of geographic information system and global positioning system in dementia care and research: a scoping review

“…These spatial analyses include spatial interpolation [57, 66, 81, 96-98, 101, 102], buffer analysis [54,67,[102][103][104][105], overlay analysis [97], land-use regression [4,106], satellite imaging [107], aerial photograph analysis [108], space syntax analysis [109], noise estimation [110], spatial linkage and aggregation [75,87,89,111,112], distancebased analysis [113]. These techniques were used to measure environmental factors such as air pollutant exposures [4,57,66,97,98,101,102,106,107], green and blue spaces [54,102,104,105,112], organophosphorus (OP) exposure [67], aluminum concentration [81], hilliness [103] and arsenic level [96]. Furthermore, the studies calculate sidewalk coverage [108] and…”

Residents' perception of living environments and self-rated health status

“…A separate problem is the removal and recycling of urban garbage and industrial waste. Poor architectural and planning decisions in the course of creation of artificial urban environment lead to the appearance of video pollution (videoecology) [1,6,9].…”

“…Many factors of the urban environment, which affect the health of citizens, have been studied. Such factors include: planning features and prevailing types of development of neighborhoods, social infrastructure, landscaping and green spaces, availability of recreational areas and recreational facilities, microclimate condition, atmospheric air pollution, impact of physical factors (noise, radiation level, electromagnetic fields), effective sanitary cleaning of districts [6,8,10].…”