title: Age and apolipoprotein E*4 allele effects on cerebrospinal fluid beta-amyloid 42 in adults with normal cognition.
abstract: BACKGROUND
  Decreased cerebrospinal fluid (CSF) beta-amyloid 42 (A beta 42) concentration, but not A beta 40 concentration, is a biomarker for Alzheimer disease. This A beta 42 concentration decrease in CSF likely reflects precipitation of A beta 42 in amyloid plaques in brain parenchyma. This pathogenic plaque deposition begins years before the clinical expression of dementia in Alzheimer disease. Normal aging and the presence of the apolipoprotein E (APOE*4) allele are the most important known risk factors for Alzheimer disease.
  
  
  OBJECTIVE
  To estimate the interactive effects of normal aging and presence of the APOE*4 allele on CSF A beta 42 concentration in adults with normal cognition across the life span.
  
  
  METHODS
  The CSF was collected in the morning after an overnight fast using Sprotte 24-g atraumatic spinal needles. The CSF A beta 42 and A beta 40 concentrations were measured in the 10th milliliter of CSF collected by sandwich enzyme-linked immunosorbent assay. The APOE genotype was determined by a restriction digest method. Subjects One hundred eighty-four community volunteers with normal cognition aged 21 to 88 years.
  
  
  RESULTS
  The CSF A beta 42, but not the A beta 40, concentration decreased significantly with age. There was a sharp decrease in CSF A beta 42 concentration beginning in the sixth decade in subjects with the APOE*4 allele. This age-associated decrease in CSF A beta 42 concentration was significantly and substantially greater in subjects with the APOE*4 allele compared with those without the APOE*4 allele.
  
  
  CONCLUSIONS
  These CSF A beta 42 findings are consistent with acceleration by the APOE*4 allele of pathogenic A beta 42 brain deposition starting in later middle age in persons with normal cognition.
authors.affiliation: VA Puget Sound Health Care System, Mental Illness Research, Education, and Clinical Center, Seattle, WA 98108, USA. peskind@u.washington.edu
authors.forename: Elaine R
authors.initials: ER
authors.lastname: Peskind
authors.forename: Ge
authors.initials: G
authors.lastname: Li
authors.forename: Jane
authors.initials: J
authors.lastname: Shofer
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Quinn
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Kaye
authors.forename: Chris M
authors.initials: CM
authors.lastname: Clark
authors.forename: Martin R
authors.initials: MR
authors.lastname: Farlow
authors.forename: Charles
authors.initials: C
authors.lastname: DeCarli
authors.forename: Murray A
authors.initials: MA
authors.lastname: Raskind
authors.forename: Gerard D
authors.initials: GD
authors.lastname: Schellenberg
authors.forename: Virginia M-Y
authors.initials: VM
authors.lastname: Lee
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Galasko
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000134:cerebrospinal fluid*; D000483:Alleles; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D015415:Biomarkers / Q000134:cerebrospinal fluid; D001921:Brain / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*
chemical_list: D016229:Amyloid beta-Peptides; D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D015415:Biomarkers; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)