title: Components of air pollution and cognitive function in middle-aged and older adults in Los Angeles.
abstract: While experiments in animals demonstrate neurotoxic effects of particulate matter (PM) and ozone (O3), epidemiologic evidence is sparse regarding the relationship between different constituencies of air pollution mixtures and cognitive function in adults. We examined cross-sectional associations between various ambient air pollutants [O3, PM2.5 and nitrogen dioxide (NO2)] and six measures of cognitive function and global cognition among healthy, cognitively intact individuals (n=1496, mean age 60.5 years) residing in the Los Angeles Basin. Air pollution exposures were assigned to each residential address in 2000-06 using a geographic information system that included monitoring data. A neuropsychological battery was used to assess cognitive function; a principal components analysis defined six domain-specific functions and a measure of global cognitive function was created. Regression models estimated effects of air pollutants on cognitive function, adjusting for age, gender, race, education, income, study and mood. Increasing exposure to PM2.5 was associated with lower verbal learning (β=-0.32 per 10 μg/m(3) PM2.5, 95% CI=-0.63, 0.00; p=0.05). Ambient exposure to NO2 >20 ppb tended to be associated with lower logical memory. Compared to the lowest level of exposure to ambient O3, exposure above 49 ppb was associated with lower executive function. Including carotid artery intima-media thickness, a measure of subclinical atherosclerosis, in models as a possible mediator did not attenuate effect estimates. This study provides support for cross-sectional associations between increasing levels of ambient O3, PM2.5 and NO2 and measures of domain-specific cognitive abilities.
authors.affiliation: Department of Epidemiology, Biostatistics & Population Medicine, School of Public Health, Loma Linda University, Loma Linda, CA, USA. Electronic address: ngatto@llu.edu.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Gatto
authors.affiliation: Department of Health Research & Policy (Epidemiology), Stanford University, Stanford, CA, USA; Department of Neurology & Neurological Sciences, Stanford University, Stanford, CA, USA.
authors.forename: Victor W
authors.initials: VW
authors.lastname: Henderson
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA; Atherosclerosis Research Unit, Department of Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA.
authors.forename: Howard N
authors.initials: HN
authors.lastname: Hodis
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA; Atherosclerosis Research Unit, Department of Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA.
authors.forename: Jan A
authors.initials: JA
authors.lastname: St John
authors.affiliation: Sonoma Technology, Inc., Petaluma, CA, USA.
authors.forename: Fred
authors.initials: F
authors.lastname: Lurmann
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA.
authors.forename: Jiu-Chiuan
authors.initials: JC
authors.lastname: Chen
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA; Atherosclerosis Research Unit, Department of Medicine, Keck School of Medicine, USC, Los Angeles, CA, USA.
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Mack
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D000397:Air Pollution / Q000009:adverse effects*; D003071:Cognition / Q000187:drug effects*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D015141:Los Angeles; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009585:Nitrogen Dioxide / Q000633:toxicity; D010126:Ozone / Q000633:toxicity; D052638:Particulate Matter / Q000633:toxicity
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D010126:Ozone; D009585:Nitrogen Dioxide
keywords: Air pollution; Cognitive dysfunction; Dementia; Ozone; Particulate matter; Verbal learning