title: Abnormalities in the pattern of platelet amyloid precursor protein forms in patients with mild cognitive impairment and Alzheimer disease.
abstract: BACKGROUND
  Patients affected by sporadic Alzheimer disease (AD) show a significant alteration of amyloid precursor protein (APP) forms in platelets when compared with patients with dementia but without AD and age-matched controls.
  
  
  OBJECTIVE
  To evaluate the ratio of platelet APP forms (APPr) in early-stage AD and mild cognitive impairment (MCI) and its potential as a biomarker for the early identification of AD.
  
  
  METHODS
  Community population-based sample of patients admitted to 4 AD centers for investigation of cognitive disturbances.
  
  
  METHODS
  Thirty-five patients with mild AD (mAD), 21 patients with very mild AD (vmAD), 30 subjects with MCI, and 25 age-matched controls were included. The APPr was evaluated by Western blot analysis in platelet homogenate.
  
  
  RESULTS
  Compared with controls (mean +/- SD, 0.93 +/- 0.3), the mean APPr was decreased in patients with mAD (0.44 +/- 0.24; P<.001) and patients with vmAD (0.49 +/- 0.3; P<.001). Regarding the MCI group, a significant decrease in APPr was found compared with controls (0.62 +/- 0.33; P<.001). Fixing a cutoff score of 0.6, sensitivity was 88.6% (31/35) for patients with mAD and 85.7% (18/21) for patients with vmAD, whereas specificity was 88% (22/25) for controls. Among patients with MCI, 18 (60%) of 30 individuals displayed APPr values below the cutoff.
  
  
  CONCLUSIONS
  Alteration of platelet APP forms is an early event in AD, and the measurement of APPr may be useful for the identification of preclinical AD in patients with MCI.
authors.affiliation: Department of Neurology, University of Brescia, Piazza Ospedale 1, 25125, Brescia, Italy. padovani@bshosp.osp.unibs.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Padovani
authors.forename: Barbara
authors.initials: B
authors.lastname: Borroni
authors.forename: Francesca
authors.initials: F
authors.lastname: Colciaghi
authors.forename: Carla
authors.initials: C
authors.lastname: Pettenati
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Cottini
authors.forename: Chiara
authors.initials: C
authors.lastname: Agosti
authors.forename: Gian Luigi
authors.initials: GL
authors.lastname: Lenzi
authors.forename: Carlo
authors.initials: C
authors.lastname: Caltagirone
authors.forename: Marco
authors.initials: M
authors.lastname: Trabucchi
authors.forename: Flaminio
authors.initials: F
authors.lastname: Cattabeni
authors.forename: Monica
authors.initials: M
authors.lastname: Di Luca
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000032:analysis*; D015415:Biomarkers; D001792:Blood Platelets / Q000737:chemistry*; D015153:Blotting, Western; D003072:Cognition Disorders / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D016564:Amyloid beta-Protein Precursor; D015415:Biomarkers