title: Reduced CSF turnover and decreased ventricular Aβ42 levels are related.
abstract: BACKGROUND
  The appearance of Aβ42 peptide deposits is admitted to be a key event in the pathogenesis of Alzheimer's disease, although amyloid deposits also occur in aged non-demented subjects. Aβ42 is a degradation product of the amyloid protein precursor (APP). It can be catabolized by several enzymes, reabsorbed by capillaries or cleared into cerebrospinal fluid (CSF). The possible involvement of a decrease in CSF turnover in A4β2 deposit formation is up to now poorly known. We therefore investigated a possible relationship between a reduced CSF turnover and the CSF levels of the A4β2 peptide.To this aim, CSF of 31 patients with decreased CSF turnover were studied. These patients presented chronic hydrocephalus communicating or obstructive, which required surgery (ventriculostomy or ventriculo-peritoneal shunt). Nine subjects had idiopathic normal pressure hydrocephalus (iNPH), and the other 22 chronic hydrocephalus from other origins (oCH).The Aβ42 peptide concentration was measured by an ELISA test in 31 ventricular CSF samples and in 5 lumbar CSF samples from patients with communicating hydrocephalus.
  
  
  RESULTS
  The 5 patients with lumbar CSF analysis had similar levels of lumbar and ventricular Aβ42. A significant reduction in Aβ42 ventricular levels was observed in 24 / 31 patients with hydrocephalus. The values were lower than 300 pg/ml in 5 out of 9 subjects with iNPH, and in 15 out of 22 subjects with oCH.
  
  
  CONCLUSIONS
  The decrease of CSF Aβ42 seems to occur independently of the surgical hydrocephalus aetiology. This suggests that a CSF reduced turnover may play an important role in the decrease of CSF Aβ42 concentration.
authors.affiliation: Department of Gerontology, CHU Amiens, France. serot.jean-marie@chu-amiens.fr
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Serot
authors.forename: Johann
authors.initials: J
authors.lastname: Peltier
authors.forename: Antony
authors.initials: A
authors.lastname: Fichten
authors.forename: Nelly
authors.initials: N
authors.lastname: Ledeme
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Bourgeois
authors.forename: Pierre
authors.initials: P
authors.lastname: Jouanny
authors.forename: Patrick
authors.initials: P
authors.lastname: Toussaint
authors.forename: Daniel
authors.initials: D
authors.lastname: Legars
authors.forename: Olivier
authors.initials: O
authors.lastname: Godefroy
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mazière
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid*; D002552:Cerebral Ventricles; D002908:Chronic Disease; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000134:cerebrospinal fluid* / Q000175:diagnosis; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid; D008161:Lumbosacral Region; D008297:Male; D010446:Peptide Fragments / Q000134:cerebrospinal fluid*
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)