title: Platelet immunoglobulin and amyloid precursor protein as potential peripheral biomarkers for Alzheimer's disease: findings from a pilot study.
abstract: BACKGROUND
  the diagnosis of dementia, in particular Alzheimer's disease (AD), is enhanced with the use of molecular biomarkers. Since cerebrospinal fluid analysis and molecular neuroimaging are not routinely used in many countries, blood biomarker molecules may be more readily applicable in a routine clinical setting.
  
  
  METHODS
  twenty-five subjects with a clinical diagnosis of AD and 26 control participants were assessed for cognitive and behavioural functioning. Platelet measures of amyloid protein precursor (APP), tau protein, clusterin, α-synuclein and immunoglobulin (Ig) were measured. Linear regression analysis for platelet proteins and cognitive and behavioural status were determined, and receiver operating characteristic (ROC) curves created to assess the discriminating power of each biochemical parameter between AD and control groups.
  
  
  RESULTS
  both AD and control subjects had similar platelet levels of measures platelet proteins, with the exception of slightly elevated Ig levels in AD subjects (P = 0.052). The latter were not related to increasing age, or extent of cognitive impairment. APP-N measures were negatively correlated with cognitive scores.
  
  
  CONCLUSIONS
  these preliminary findings suggest that platelet measures of the traditional biomarkers for AD are feasible in the periphery. The measures of platelet APP-N and Ig, in particular, merit further study in a larger cohort of AD and control subjects.
authors.affiliation: Institute for Ageing and Health, Campus for Ageing and Vitality, Newcastle University, Newcastle, UK. elizabeta.mukaetova-ladinska@ncl.ac.uk
authors.forename: Elizabeta B
authors.initials: EB
authors.lastname: Mukaetova-Ladinska
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Abdel-All
authors.forename: Steven
authors.initials: S
authors.lastname: Dodds
authors.forename: Joana
authors.initials: J
authors.lastname: Andrade
authors.forename: Joaquim
authors.initials: J
authors.lastname: Alves da Silva
authors.forename: Raj N
authors.initials: RN
authors.lastname: Kalaria
authors.forename: John T
authors.initials: JT
authors.lastname: O'Brien
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood / Q000175:diagnosis* / Q000276:immunology / Q000523:psychology; D016564:Amyloid beta-Protein Precursor / Q000097:blood*; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D001792:Blood Platelets / Q000276:immunology* / Q000378:metabolism*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003071:Cognition; D016002:Discriminant Analysis; D004739:England; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000097:blood*; D016014:Linear Models; D008297:Male; D009483:Neuropsychological Tests; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve
chemical_list: C545487:APP protein, human; D016564:Amyloid beta-Protein Precursor; D015415:Biomarkers; D007136:Immunoglobulins