title: Traffic pollution exposure is associated with altered brain connectivity in school children.
abstract: Children are more vulnerable to the effects of environmental elements due to their active developmental processes. Exposure to urban air pollution has been associated with poorer cognitive performance, which is thought to be a result of direct interference with brain maturation. We aimed to assess the extent of such potential effects of urban pollution on child brain maturation using general indicators of vehicle exhaust measured in the school environment and a comprehensive imaging evaluation. A group of 263 children, aged 8 to 12 years, underwent MRI to quantify regional brain volumes, tissue composition, myelination, cortical thickness, neural tract architecture, membrane metabolites, functional connectivity in major neural networks and activation/deactivation dynamics during a sensory task. A combined measurement of elemental carbon and NO2 was used as a putative marker of vehicle exhaust. Air pollution exposure was associated with brain changes of a functional nature, with no evident effect on brain anatomy, structure or membrane metabolites. Specifically, a higher content of pollutants was associated with lower functional integration and segregation in key brain networks relevant to both inner mental processes (the default mode network) and stimulus-driven mental operations. Age and performance (motor response speed) both showed the opposite effect to that of pollution, thus indicating that higher exposure is associated with slower brain maturation. In conclusion, urban air pollution appears to adversely affect brain maturation in a critical age with changes specifically concerning the functional domain.
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain; Centro Investigación Biomédica en Red de Salud Mental, CIBERSAM G21, Barcelona, Spain. Electronic address: 21404jpn@comb.cat.
authors.forename: Jesus
authors.initials: J
authors.lastname: Pujol
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.
authors.forename: Gerard
authors.initials: G
authors.lastname: Martínez-Vilavella
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.
authors.forename: Dídac
authors.initials: D
authors.lastname: Macià
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Fenoll
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Pompeu Fabra University, Barcelona, Catalonia, Spain; Ciber on Epidemiology and Public Health (CIBERESP), Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: Alvarez-Pedrerol
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Pompeu Fabra University, Barcelona, Catalonia, Spain; Ciber on Epidemiology and Public Health (CIBERESP), Spain; Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Catalonia, Spain.
authors.forename: Ioar
authors.initials: I
authors.lastname: Rivas
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Pompeu Fabra University, Barcelona, Catalonia, Spain; Ciber on Epidemiology and Public Health (CIBERESP), Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Forns
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Blanco-Hinojo
authors.affiliation: Radiology Department, Hospital del Mar, Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Capellades
authors.affiliation: Institute of Environmental Assessment and Water Research (IDAEA-CSIC), Barcelona, Catalonia, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Querol
authors.affiliation: MRI Research Unit, Hospital del Mar, Barcelona, Spain; Department of Clinical and Health Psychology, Autonomous University of Barcelona, Spain; Instituto Universitario de Neurorrehabilitación Guttmann, Badalona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: Deus
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain; Pompeu Fabra University, Barcelona, Catalonia, Spain; Ciber on Epidemiology and Public Health (CIBERESP), Spain; IMIM (Hospital del Mar Medical Research Institute), Barcelona, Catalonia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Sunyer
mesh_terms: D000397:Air Pollution / Q000009:adverse effects*; D001921:Brain / Q000187:drug effects / Q000503:physiopathology*; D002648:Child; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology*; D001335:Vehicle Emissions / Q000633:toxicity*
chemical_list: D001335:Vehicle Emissions
keywords: Air pollution; Brain development; Functional MRI; Functional connectivity