Air pollution in relation to brain health indicators and global cognitive functioning in patients with cardiovascular disorders along the heart-brain axis

Background/Introduction Exploring, understanding, and preventing the effects of exposure to air pollutants on the brain, and possible links to cognitive functioning, have been indicated as major global health challenges that urgently need to be addressed. Yet, relatively little work has been conducted to examine the associations of air pollution with indicators of brain health that are potentially related to cognitive functioning in patients who are at increased risk to develop cognitive impairments. Purpose This study aimed to examine cross-sectional and longitudinal associations of air pollution with global cognitive functioning, white matter hyperintensities (WMH), total brain volume (TBV), and cerebral blood flow (CBF) in individuals without or with heart failure, carotid occlusive disease, or vascular cognitive impairment. Additionally, this study examined whether the cross-sectional associations of air pollution with global cognitive functioning were mediated by WMH, TBV, and CBF. Methods For the cross-sectional and longitudinal analyses, we used data from 341 and 180 participants of the Dutch multi-center Heart-Brain Study, respectively. Cognitive functioning was measured using neuropsychological tests at baseline and two-year follow-up. Brain Magnetic Resonance Imaging provided WMH and TBV in mL, and CBF in mL/100g/min. WMH and TBV were divided by total intracranial volume. Annual average outdoor concentrations of particulate matter with diameters <2.5µm (PM2.5) and <10.0µm (PM10), and nitrogen dioxide (NO2) in µg/m3 in residential six-digit postal code areas were linked to participants at baseline. Adjusted multi-level regression analyses were applied to assess the associations of interest. Results No significant cross-sectional (βPM2.5=0.014, 95% CI=-0.076-0.104; βPM10=0.034, 95% CI=-0.043-0.111; βNO2=0.020, 95% CI=-0.004-0.045) and longitudinal associations (βPM2.5=0.041, 95% CI=-0.029-0.110; βPM10=0.016, 95% CI=-0.045-0.078; βNO2=-0.001, 95% CI=-0.022-0.022) of air pollution with global cognitive functioning were observed. No significant associations of air pollution with WMH, TBV, and CBF were found. The associations of PM2.5, PM10 and NO2 with global cognitive functioning were not significantly mediated by WMH, TBV, and CBF. Conclusions No supportive evidence was found for associations of air pollution with global cognitive functioning, WMH, TBV and CBF in healthy and vascularly compromised individuals.