Long-term air pollution and traffic noise exposures and cognitive function:A cross-sectional analysis of the Heinz Nixdorf Recall study

ABSTRACT

Investigations of adverse effects of air pollution (AP) and ambient noise on cognitive functions are apparently scarce, and findings seem to be inconsistent. The aim of this study was to examine the associations of long-term exposure to AP and traffic noise with cognitive performance. At the second examination of the population-based Heinz Nixdorf Recall study (2006–2008), cognitive performance was evaluated in 4086 participants. Long-term residential exposure to size-specific particulate matter (PM) and nitrogen oxides (NOx) with land use regression, to and traffic noise (weighted 24-h (L_DEN) and nighttime (L_NIGHT) means), was assessed according to the European Union (EU) Directive 2002/49/EC. Multiple regression models were calculated for the relationship of environmental exposures with a global cognitive score (GCS) and in five cognitive subtests, using single- and two-exposure models. In fully adjusted models, several AP metrics were negatively associated with four of five subtests and with GCS. For example, an interquartile range increase in PM_2.5 was correlated with verbal fluency, labyrinth test, and immediate and delayed verbal recall. A 10 dB(A) elevation in L_DEN and L_NIGHT was associated with GCS. Similar but not significant associations were found for the cognitive subtests. In two-exposure models including noise and air pollution simultaneously, the associations did not change markedly for air pollution, but attenuated numerically for noise. Long-term exposures to AP and traffic noise are negatively correlated with subtests related to memory and executive functions. There appears to be little evidence for mutual confounding.

Funding

Lilian Tzivian gratefully acknowledges support by a postdoctoral fellowship from the Environmental and Health Fund, Jerusalem, Israel. We thank the Heinz Nixdorf Foundation (chairman: M. Nixdorf) for its generous support of this study. This study is also supported by the German Ministry of Education and Science and by the German Research Council (DFG; JO 170/8-1, HO 3314/2-1, HO 3314/2-3, HO 3314/4-3, ER 155/6-2).

We are indebted to the investigative group and the study personnel of the Heinz Nixdorf Recall study. We also thank the North Rhine–Westphalia State Agency for Nature, Environment and Consumer Protection for providing emission data for North Rhine–Westphalia and the city administrations of Mülheim, Essen and Bochum for providing noise exposure data.

Conflict of Interest

No author declares a conflict of interest.

Additional information

Funding

Lilian Tzivian gratefully acknowledges support by a postdoctoral fellowship from the Environmental and Health Fund, Jerusalem, Israel. We thank the Heinz Nixdorf Foundation (chairman: M. Nixdorf) for its generous support of this study. This study is also supported by the German Ministry of Education and Science and by the German Research Council (DFG; JO 170/8-1, HO 3314/2-1, HO 3314/2-3, HO 3314/4-3, ER 155/6-2). We are indebted to the investigative group and the study personnel of the Heinz Nixdorf Recall study. We also thank the North Rhine–Westphalia State Agency for Nature, Environment and Consumer Protection for providing emission data for North Rhine–Westphalia and the city administrations of Mülheim, Essen and Bochum for providing noise exposure data.