Residential natural outdoor environment and stroke incidence in older adults in Southern Sweden: A register RELOC-AGE cohort study

BACKGROUND: Stroke is a leading cause of morbidity and mortality worldwide, particularly in later life. While prior research suggests that proximity to green spaces may reduce stroke incidence and support post-stroke recovery, the relationship between the natural outdoor environment and stroke incidence remains underexplored. We investigated the associations between the residential natural outdoor environment and stroke incidence among older adults. METHODS: Utilizing Register RELOC-AGE data, a cohort study was conducted among 259,769 older adults aged 60+ residing in the Scania region, Southern Sweden. Data from Swedish population registers in 2008, and area-aggregated Perceived Sensory Dimension Score (PSD-score) derived from the Scania outdoor environment database (ScOut) were categorised into tertiles (high, intermediate and low) reflecting the natural outdoor environment close to residence. Incident strokes per 100,000 person-years were assessed between 2009 and 2019. Cox proportional hazard (multi-) exposure models adjusted for socioeconomic; demographic and health were used to examine associations between the PSD-score and stroke incidence. RESULTS: During the 10-year follow-up, 23,509 individuals experienced a stroke. Stroke incidence was the lowest among those with a high PSD-score (overall incidence rate of 668/100,000) compared with those with a low and intermediate PSD-score (incidence of 733/100,000 and 720/100,000, respectively). High PSD-score was associated with a lower hazard of stroke (adjusted HR 0.92, 95% CI 0.89-0.95), also when additionally adjusted for multiple exposures (adjusted HR 0.95, 95% CI 0.92-0.98). CONCLUSION: The findings suggest that living in more favourable residential natural outdoor environment are protective against stroke, consistent across sexes. Although there was an indication for a protective effect for those living in high PSD-score areas in urban municipalities, interaction analyses indicated statistical uncertainty. These results highlight the potential relevance of natural outdoor environments for age-friendly and public health planning. Future research should investigate the mechanisms underlying these associations and the role of the natural outdoor environment in post-stroke recovery, while also considering stroke severity.