title: Ambient air pollution and neurotoxicity on brain structure: Evidence from women's health initiative memory study.
abstract: OBJECTIVE
  The aim of this study was to examine the putative adverse effects of ambient fine particulate matter (PM2.5 : PM with aerodynamic diameters <2.5μm) on brain volumes in older women.
  
  
  METHODS
  We conducted a prospective study of 1,403 community-dwelling older women without dementia enrolled in the Women's Health Initiative Memory Study, 1996-1998. Structural brain magnetic resonance imaging scans were performed at the age of 71-89 years in 2005-2006 to obtain volumetric measures of gray matter (GM) and normal-appearing white matter (WM). Given residential histories and air monitoring data, we used a spatiotemporal model to estimate cumulative PM2.5 exposure in 1999-2006. Multiple linear regression was employed to evaluate the associations between PM2.5 and brain volumes, adjusting for intracranial volumes and potential confounders.
  
  
  RESULTS
  Older women with greater PM2.5 exposures had significantly smaller WM, but not GM, volumes, independent of geographical region, demographics, socioeconomic status, lifestyles, and clinical characteristics, including cardiovascular risk factors. For each interquartile increment (3.49μg/m(3) ) of cumulative PM2.5 exposure, the average WM volume (WMV; 95% confidence interval) was 6.23cm(3) (3.72-8.74) smaller in the total brain and 4.47cm(3) (2.27-6.67) lower in the association areas, equivalent to 1 to 2 years of brain aging. The adverse PM2.5 effects on smaller WMVs were present in frontal and temporal lobes and corpus callosum (all p values <0.01). Hippocampal volumes did not differ by PM2.5 exposure.
  
  
  CONCLUSIONS
  PM2.5 exposure may contribute to WM loss in older women. Future studies are needed to determine whether exposures result in myelination disturbance, disruption of axonal integrity, damages to oligodendrocytes, or other WM neuropathologies.
authors.affiliation: Department of Preventive Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA.
authors.forename: Jiu-Chiuan
authors.initials: JC
authors.lastname: Chen
authors.affiliation: Department of Preventive Medicine, University of Southern California, Keck School of Medicine, Los Angeles, CA.
authors.forename: Xinhui
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Epidemiology, Brown University School of Public Health, Providence, RI.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Wellenius
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC.
authors.forename: Marc L
authors.initials: ML
authors.lastname: Serre
authors.affiliation: Department of Psychology, University of Wisconsin, Milwaukee, WI.
authors.forename: Ira
authors.initials: I
authors.lastname: Driscoll
authors.affiliation: Department of Biostatistical Sciences, Division of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, NC.
authors.forename: Ramon
authors.initials: R
authors.lastname: Casanova
authors.affiliation: Department of Psychology, University of Southern California, Los Angeles, CA.
authors.forename: John J
authors.initials: JJ
authors.lastname: McArdle
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA.
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.affiliation: Department of Neurology, University of Southern California, Keck School of Medicine, Los Angeles, CA.
authors.forename: Helena C
authors.initials: HC
authors.lastname: Chui
authors.affiliation: Department of Biostatistical Sciences, Division of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, NC.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Espeland
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000397:Air Pollution / Q000009:adverse effects*; D001921:Brain / Q000473:pathology*; D015331:Cohort Studies; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008569:Memory Disorders / Q000175:diagnosis* / Q000209:etiology*; D009929:Organ Size; D052638:Particulate Matter / Q000009:adverse effects*; D011446:Prospective Studies; D016387:Women's Health / Q000639:trends
chemical_list: D052638:Particulate Matter