title: Lead exposure and rate of change in cognitive function in older women.
abstract: BACKGROUND
  Higher long-term cumulative lead exposure predicts faster cognitive decline in older men, but evidence of an association in women is lacking.
  
  
  OBJECTIVE
  To determine if there is an association between lead exposure and cognitive decline in women.
  
  
  METHODS
  This study considers a sample of 584 women from the Nurses' Health Study who live in or near Boston, Massachusetts. We quantified lead exposure using biomarkers of lead exposure assessed in 1993-2004 and evaluated cognitive decline by repeated performance on a telephone battery of cognitive tests primarily assessing learning, memory, executive function, and attention completed in 1995-2008. All cognitive test scores were z-transformed for use in analyses. We used linear mixed models with random effects to quantify the association between each lead biomarker and change in cognition overall and on each individual test.
  
  
  RESULTS
  Consideration of individual tests showed greater cognitive decline with increased tibia lead concentrations, a measure of long-term cumulative exposure, for story memory and category fluency. The estimated excess annual decline in overall cognitive test z-score per SD increase in tibia bone lead concentration was suggestive, although the confidence intervals included the null (0.024 standard units, 95% confidence interval: -0.053, 0.004 - an additional decline in function equivalent to being 0.33 years older). We found little support for associations between cognitive decline and patella or blood lead, which provide integrated measures of exposure over shorter timeframes.
  
  
  CONCLUSIONS
  Long-term cumulative lead exposure may be weakly associated with faster cognitive decline in community-dwelling women, at least in some cognitive domains.
authors: Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Electronic address: melindacpower@gmail.com.
authors: Melinda C
authors: MC
authors: Power
authors: Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Channing Division of Network Medicine, Department of Medicine at Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA. Electronic address: resak@channing.harvard.edu.
authors: Susan
authors: S
authors: Korrick
authors: Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Department of Biostatistics, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Electronic address: etchetge@hsph.harvard.edu.
authors: Eric J
authors: EJ
authors: Tchetgen Tchetgen
authors: Purdue University, School of Health Sciences, College of Health and Human Sciences, 700 W. State Street, West Lafayette, IN 47907, USA. Electronic address: hnie@purdue.edu.
authors: Linda H
authors: LH
authors: Nie
authors: Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Channing Division of Network Medicine, Department of Medicine at Brigham and Women's Hospital and Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA. Electronic address: phfrg@channing.harvard.edu.
authors: Francine
authors: F
authors: Grodstein
authors: Department of Environmental Health Sciences at the University of Michigan School of Public Health, 1415 Washington Heights, Ann Arbor, MI 48109, USA. Electronic address: howard.hu@utoronto.ca.
authors: Howard
authors: H
authors: Hu
authors: Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Institute of Healthy Aging and Department of Internal Medicine, Rush University Medical Center, 1653 W. Congress Parkway, Chicago, IL 60612, USA. Electronic address: jweuve@hsph.harvard.edu.
authors: Jennifer
authors: J
authors: Weuve
authors: Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Electronic address: joel@hsph.harvard.edu.
authors: Joel
authors: J
authors: Schwartz
authors: Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA; Department of Environmental Health, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Electronic address: mweissko@hsph.harvard.edu.
authors: Marc G
authors: MG
authors: Weisskopf
mesh_terms: D000368:Aged; D015519:Bone Density; D003071:Cognition / Q000187:drug effects*; D003072:Cognition Disorders / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D004785:Environmental Pollutants / Q000032:analysis / Q000097:blood* / Q000633:toxicity; D005260:Female; D006801:Humans; D007854:Lead / Q000032:analysis / Q000097:blood* / Q000633:toxicity; D016014:Linear Models; D008404:Massachusetts; D009483:Neuropsychological Tests; D011859:Radiography; D013977:Tibia / Q000737:chemistry / Q000000981:diagnostic imaging
chemical_list: D004785:Environmental Pollutants; D007854:Lead
keywords: Cognition; Cognitive decline; Cohort; Epidemiology; Lead