Association between Long-Term Air Pollution, Chronic Traffic Noise, and Resting-State Functional Connectivity in the 1000BRAINS Study

Abstract

BACKGROUND: Older adults show a high variability in cognitive performance that cannot be explained by aging alone. Although research has linked air pollution and noise to cognitive impairment and structural brain alterations, the potential impact of air pollution and noise on functional brain organization is unknown. OBJECTIVE: This study examined the associations between long-term air pollution and traffic noise with measures of functional brain organization in older adults. We hypothesize that exposures to high air pollution and noise levels are associated with age-like changes in functional brain organiza-tion, shown by less segregated brain networks. METHODS: Data from 574 participants (44.1% female, 56–85 years of age) in the German 1000BRAINS study (2011–2015) were analyzed. Exposure to particulate matter (PM10, PM2:5, and PM2:5 absorbance), accumulation mode particle number (PNAM ), and nitrogen dioxide (NO2 ) was estimated applying land-use regression and chemistry transport models. Noise exposures were assessed as weighted 24-h (Lden ) and nighttime (Lnight ) means. Functional brain organization of seven established brain networks (visual, sensorimotor, dorsal and ventral attention, limbic, frontoparietal and default network) was assessed using resting-state functional brain imaging data. To assess functional brain organization, we determined the degree of segregation between networks by comparing the strength of functional connections within and between networks. We estimated associations between air pollution and noise exposure with network segregation, applying multiple linear regression models adjusted for age, sex, socioeconomic status, and lifestyle variables. RESULTS: Overall, small associations of high exposures with lesser segregated networks were visible. For the sensorimotor networks, we observed small associations between high air pollution and noise and lower network segregation, which had a similar effect size as a 1-y increase in age [e.g., in sensorimotor network, −0:006 (95% CI: −0:021, 0.009) per 0.3 × 10−5 =m increase in PM2:5 absorbance and −0:004 (95% CI: −0:006, −0:002) per 1-y age increase]. CONCLUSION: High exposure to air pollution and noise was associated with less segregated functional brain networks.