title: Tau is reduced in AD plasma and validation of employed ELISA methods.
abstract: OBJECTIVE
  Measure total tau levels in the circulation of living humans, validate the methods employed and determine if there are consistent differences in total tau levels between normal controls and individuals with mild cognitive impairment (MCI) and/or Alzheimer's disease (AD).
  
  
  METHODS
  Employing ELISA methods, validated by Western bolts using three separate tau antibodies, we quantified total tau levels in serially collected serum and plasma samples from individuals longitudinally evaluated for cognitive performance.
  
  
  RESULTS
  We identified substantial levels of tau in human circulation using plasma, but not serum. The measurement of authentic tau protein was verified by Western blots using a C-terminal specific antibody, an N-terminal specific antibody and antibody used in the commercially available ELISA kit. We revealed a significant decrease in plasma levels of total tau among subjects with MCI compared to cognitively normal controls, with a further highly significant reduction in AD patients compared to both MCI and normal controls. We also found a significant positive correlation between changing levels of plasma tau and cognitive performance within the entire population and among AD patients.
  
  
  CONCLUSIONS
  The data suggest that changes in circulating tau levels quantified in plasma samples, but not serum samples, may represent a viable biomarker for tracking the progression of AD and the efficacy of medications in its treatment.
authors: Roberts Laboratory for Neurodegenerative Disease Research, Banner Sun Health Research Institute Sun City, AZ, USA.
authors: D Larry
authors: DL
authors: Sparks
authors: Richard J
authors: RJ
authors: Kryscio
authors: Marwan N
authors: MN
authors: Sabbagh
authors: Chuck
authors: C
authors: Ziolkowski
authors: Yushun
authors: Y
authors: Lin
authors: Lisa M
authors: LM
authors: Sparks
authors: Carolyn
authors: C
authors: Liebsack
authors: Sherry
authors: S
authors: Johnson-Traver
keywords: Alzheimer’s disease; Circulating tau levels; mild cognitive impairment
references: Acta Neurol Scand. 2011 Apr;123(4):252-6
references: 20597867
references: Neurology. 1984 Jul;34(7):939-44
references: 6610841
references: Acta Anaesthesiol Scand. 2011 Oct;55(9):1132-8
references: 22092212
references: J Mol Neurosci. 2011 Mar;43(3):241-5
references: 20549384
references: Arch Neurol. 2001 Dec;58(12):1985-92
references: 11735772
references: Ann N Y Acad Sci. 2007 Feb;1097:114-45
references: 17413016
references: Dement Geriatr Cogn Disord. 1999 Nov-Dec;10(6):442-5
references: 10559557
references: Alzheimers Dement. 2010 May;6(3):230-8
references: 20451871
references: Exp Gerontol. 2010 Jan;45(1):30-40
references: 19853650
references: Int J Alzheimers Dis. 2011 Apr 17;2011:987023
references: 21559186
references: Lancet Neurol. 2006 Mar;5(3):228-34
references: 16488378
references: J Psychiatr Res. 1975 Nov;12(3):189-98
references: 1202204
references: Neurobiol Aging. 2009 Jul;30(7):1069-77
references: 18068270
references: J Neurol. 2010 Apr;257(4):609-14
references: 19921301
references: J Intern Med. 2004 Sep;256(3):183-94
references: 15324362
references: J Surg Res. 2010 May 15;160(2):302-7
references: 19345376
references: Dement Geriatr Cogn Disord. 2007;23(5):316-20
references: 17374949
references: Clin Chem. 2005 Feb;51(2):336-45
references: 15563479
references: Nat Rev Neurol. 2010 Mar;6(3):131-44
references: 20157306
references: J Alzheimers Dis. 2009;18(2):331-7
references: 19584438
references: Ann Neurol. 2009 Apr;65(4):403-13
references: 19296504
references: Neurologia. 2000 Mar;15(3):93-101
references: 10846869
references: Resuscitation. 2010 Sep;81(9):1205-8
references: 20598429
references: Neurosci Lett. 2006 Dec 20;410(2):90-3
references: 17095156
references: Nat Rev Drug Discov. 2007 Apr;6(4):295-303
references: 17347655
references: J Neurol. 2011 Aug;258(8):1464-8
references: 21360196
references: Am J Emerg Med. 2010 May;28(4):399-403
references: 20466216
references: Neurology. 2007 Dec 11;69(24):2205-12
references: 18071141
references: Neurology. 2008 Jul 8;71(2):85-92
references: 18509095
references: Arch Neurol. 2010 Aug;67(8):949-56
references: 20697045
references: Clin Neurol Neurosurg. 2006 Sep;108(6):558-63
references: 16457947