Urban green space and the risks of dementia and stroke.

Introduction: It is unknown whether urban green space is associated with reduced risk of major neurological conditions, especially dementia and stroke.
Methods: Retrospective, population-based cohorts were created for each study outcome, including 1.7 and 4.3 million adults in Ontario, Canada for dementia and stroke, respectively. Residential green space was quantified using the satellite-derived Normalized Difference Vegetation Index. Incidence was ascertained using health administrative data with validated algorithms. Mixed-effects Cox models were used to estimate hazard ratios per interquartile range increase in green space exposure.
Results: Between 2001 and 2013, 219,013 individuals were diagnosed with dementia and 89,958 had a stroke. The hazard ratio per interquartile range increase in green space was 0.97 (95% CI: 0.96-0.98) for dementia and 0.96 (0.95-0.98) for stroke. Estimates remained generally consistent in sensitivity analyses.
Discussion: Increased exposure to urban green space was associated with reduced incidence of dementia and stroke. To our knowledge, this is the first population-based cohort study to assess these relationships.
Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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