How air pollution alters brain development: the role of neuroinflammation

Abstract

The present review synthesizes lines of emerging evidence showing how several samples of children populations living in large cities around the world suffer to some degree neural, behavioral and cognitive changes associated with air pollution exposure. The breakdown of natural barriers warding against the entry of toxic particles, including the nasal, gut and lung epithelial barriers, as well as widespread breakdown of the blood-brain barrier facilitatethe passage of airborne pollutants into the body of young urban residents. Extensive neuroinflammation contributes to cell loss within the central nervous system, and likely is a crucial mechanism by which cognitive deficits may arise. Although subtle, neurocognitive effects of air pollution are substantial, apparent across all populations, and potentially clinically relevant as early evidence of evolving neurodegenerative changes. The diffuse nature of the neuroinflammation risk suggests an integrated neuroscientific approach incorporating current clinical, cognitive, neurophysiological, radiological and epidemiologic research. Neuropediatric air pollution research requires extensive multidisciplinary collaborations to accomplish the goal of protecting exposed children through multidimensional interventions having both broad impact and reach. While intervening by improving environmental quality at a global scale is imperative, we also need to devise efficient strategies on how the neurocognitive effects on local pediatric populations should be monitored.

Keywords: Air pollution; Child brain development; Children's health; Early prevention and intervention; Neurodegeneration; Neuroinflammation; Public health.

Figure 1.

A. Hypothesized progression by which air pollution may negatively impact the central nervous system, regarding the interaction of compromised epithelial barriers, normally protective against such pollutants, and a pro-inflammatory state of the body’s immune system. B. Sagittal view of magnetic resonance image of neuroinflammation in cortical structures in a male Mexico City resident aged 10 (Courtesy of Professor Lilian Calderón-Garcidueñas). Yellow = prefrontal cortex; Blue = olfactory bulb; Green = brainstem. Red arrows indicate plausible vectors by which airborne pollutants may enter the central nervous system and contribute to neuroinflammation/ cell loss. PM = particulate matter, BBB = blood-brain barrier.