title: ABO blood type, factor VIII, and incident cognitive impairment in the REGARDS cohort.
abstract: OBJECTIVE
  To assess the relationships among ABO group, factor VIII (FVIII), and incident cognitive impairment in a large, prospective cohort study of black and white adults in the United States using a nested case-control design.
  
  
  METHODS
  Incident cognitive impairment was defined using cognitive domain tests over a mean follow-up of 3.4 years. ABO blood group was measured by genotyping in a nested case-control sample of 495 cases with cognitive impairment and 587 controls.
  
  
  RESULTS
  Those with blood group AB and those with higher FVIII had an increased risk of cognitive impairment, adjusting for age, race, region, and sex (respective odds ratios 1.82, 95% confidence interval [CI] 1.15-2.90; and 1.24, 95% CI 1.10-1.38 for 40 IU/dL higher FVIII). Mean FVIII was higher in those with blood type AB (142 IU/dL; 95% CI 119-165) compared with O (104 IU/dL; 95% CI 101-107), and FVIII mediated 18% of the association between AB group and incident cognitive impairment (95% CI for mediation -30% to 68%).
  
  
  CONCLUSIONS
  Blood group AB and higher FVIII were associated with increased incidence of cognitive impairment in this prospective study. The association of blood group AB with incident cognitive impairment was not significantly mediated by FVIII levels.
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis.
authors.forename: Kristine S
authors.initials: KS
authors.lastname: Alexander
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis.
authors.forename: Neil A
authors.initials: NA
authors.lastname: Zakai
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gillett
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: McClure
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis.
authors.forename: Virginia
authors.initials: V
authors.lastname: Wadley
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis.
authors.forename: Fred
authors.initials: F
authors.lastname: Unverzagt
authors.affiliation: From the Departments of Medicine (K.S.A., N.A.Z., S.G., M.C.) and Pathology (N.A.Z., M.C.), University of Vermont, Burlington; School of Public Health (L.A.M.) and Division of Gerontology, Geriatrics and Palliative Care, Department of Medicine (V.W.), University of Alabama at Birmingham; and Department of Psychiatry (F.U.), Indiana University School of Medicine, Indianapolis. mary.cushman@uvm.edu.
authors.forename: Mary
authors.initials: M
authors.lastname: Cushman
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D001741:Black or African American; D001784:Blood Gas Analysis; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000097:blood* / Q000453:epidemiology* / Q000235:genetics; D005169:Factor VIII / Q000378:metabolism*; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease; D060005:Genotyping Techniques; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011446:Prospective Studies; D014481:United States / Q000453:epidemiology; D044465:White People
chemical_list: D000017:ABO Blood-Group System; D005169:Factor VIII