Air pollution, neighbourhood walkability and cerebrovascular small vessel disease in patients with cardiovascular disorders along the heart-brain axis

Abstract

Background

We investigated if ambient air pollution and neighbourhood walkability associate with presence and progression of cerebral small vessel disease (CSVD) in patients with cardiovascular disorders along the heart-brain axis.

Methods

Data from patients with heart failure, carotid occlusive disease, or vascular cognitive impairment (30% women; mean age 69.0 years) of the Heart-Brain Connection study were used. Brain parenchymal fraction (BPF), white matter hyperintensity fraction (WMH), cerebral blood flow (CBF), and incident vascular lesions were assessed with 3T brain MRI at baseline (n = 300) and at two years follow-up (n = 181). Incident clinical cerebrovascular events were assessed with questionnaires and telephone interviews up to five years. Annual residential nitrogen dioxide (NO₂; µg/m³) concentration was linked to participants at baseline. Neighbourhood walkability was measured using the Dutch walkability index within a 500-m Euclidean buffer around each residential-area centroid (range 0–100). Associations were analyzed using age- and sex-adjusted logistic regression and repeated-measures linear mixed models.

Results

At baseline, no association was found between NO₂ or walkability and BPF, WMH, CBF, infarcts or microbleeds. Walkability (per 10 units) was associated with lower odds for having infarcts at baseline (OR 0.82, 95%CI 0.96–0.99) and attenuated age-related WMH increases by 0.01 SD (95%CI 0.00–0.02) per year. In longitudinal analyses, no associations between NO₂ or walkability and progression of vascular brain lesions, cerebrovascular events, or mortality were found.

Conclusion

Although air pollution and neighbourhood walkability were not strongly associated with CSVD progression, stroke, or mortality, higher walkability appeared to modestly attenuate age-related increases in WMH.