title: Elevated platelet beta-secretase activity in mild cognitive impairment.
abstract: OBJECTIVE
  We have recently reported that platelet activity of the rate-limiting enzyme for beta-amyloid peptide production is elevated in established Alzheimer's disease. Laboratory investigation of the very early stages of dementia provides an opportunity to investigate pathological mechanisms before advanced disease hinders interpretation. Mild cognitive impairment (MCI) exists prior to obvious dementia, and is associated with increased risk of conversion to overt disease.
  
  
  METHODS
  We developed and used a fluorimetric assay to quantify platelet membrane beta-secretase activity in 52 patients with MCI and 75 controls.
  
  
  RESULTS
  Platelet membrane beta-secretase activity was 24% higher in individuals with MCI compared to controls (p = 0.001, unpaired t test with Welch correction).
  
  
  CONCLUSIONS
  Elevated platelet beta-secretase activity in subjects with MCI is an area for further study in relation to the etiology and diagnosis of MCI.
authors.affiliation: Division of Psychiatry and Neuroscience, School of Medicine and Dentistry, Queen's University Belfast, Belfast, UK.
authors.forename: W W
authors.initials: WW
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Todd
authors.forename: D
authors.initials: D
authors.lastname: Craig
authors.forename: A P
authors.initials: AP
authors.lastname: Passmore
authors.forename: D T R
authors.initials: DT
authors.lastname: Coulson
authors.forename: S
authors.initials: S
authors.lastname: Murphy
authors.forename: G B
authors.initials: GB
authors.lastname: Irvine
authors.forename: J A
authors.initials: JA
authors.lastname: Johnston
mesh_terms: D000368:Aged; D053829:Amyloid Precursor Protein Secretases / Q000097:blood*; D001792:Blood Platelets / Q000378:metabolism*; D001921:Brain / Q000473:pathology; D003072:Cognition Disorders / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D009410:Nerve Degeneration / Q000473:pathology; D009483:Neuropsychological Tests; D012372:ROC Curve; D012720:Severity of Illness Index
chemical_list: D053829:Amyloid Precursor Protein Secretases