Dementia mimicking Alzheimer's disease Owing to a tau mutation: CSF and PET findings

Alzheimer Dis Assoc Disord. Jul-Sep 2010;24(3):303-7. doi: 10.1097/WAD.0b013e3181cf35ec.


The objective of the study was to illustrate the utility of positron emission tomography (PET) imaging using [C]PIB and [F]FDDNP together with cerebrospinal fluid (CSF) measures of amyloid-beta1 to 42 (Abeta42), total tau (t-tau) and tau phosphorylated at threonine 181 (p-tau) in the in vivo diagnosis of specific dementia syndromes. Two siblings fulfilling diagnostic criteria for familial Alzheimer's disease (AD) were investigated using [C]PIB and [F]FDDNP PET in combination with CSF measures of Abeta42, t-tau and p-tau. PET data were compared with paired [C]PIB and [F]FDDNP data from age-matched sporadic AD patients (n=9) and healthy controls (n=6). [C]PIB retention and CSF levels of Abeta42 in both patients resembled those of controls suggesting the presence of nonamyloid pathology. Genetic testing confirmed the absence of mutations in the presenilin 1 gene in 1 patient; subsequent testing revealed the R406W tau mutation in both individuals leading to a diagnosis of frontotemporal dementia [F]FDDNP retention broadly correlated with CSF levels of t-tau and p-tau. Despite both individuals harbouring the same mutation, [F]FDDNP retention and CSF t-tau and p-tau were elevated in 1 patient, but not in the other. [C]PIB imaging and CSF measures of Abeta42 are useful in refuting the presence of underlying amyloid pathology. This, in combination with elevated levels of CSF t-tau and p-tau, has potential value in differential diagnosis of frontotemporal dementia from AD.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alzheimer Disease / cerebrospinal fluid*
  • Alzheimer Disease / diagnosis
  • Alzheimer Disease / diagnostic imaging
  • Alzheimer Disease / genetics
  • Amyloid beta-Peptides / cerebrospinal fluid
  • Aniline Compounds
  • Benzothiazoles
  • Biomarkers / cerebrospinal fluid
  • Brain / pathology
  • Dementia / cerebrospinal fluid
  • Dementia / diagnosis
  • Dementia / diagnostic imaging
  • Diagnosis, Differential
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nitriles
  • Peptide Fragments / cerebrospinal fluid
  • Positron-Emission Tomography / methods
  • Presenilin-1 / genetics
  • Thiazoles
  • Threonine / metabolism
  • tau Proteins / cerebrospinal fluid*
  • tau Proteins / genetics*
  • tau Proteins / metabolism


  • 2-(1-(6-((2-fluoroethyl)(methyl)amino)-2-naphthyl)ethylidene)malononitrile
  • 2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole
  • Amyloid beta-Peptides
  • Aniline Compounds
  • Benzothiazoles
  • Biomarkers
  • MAPT protein, human
  • Nitriles
  • PSEN1 protein, human
  • Peptide Fragments
  • Presenilin-1
  • Thiazoles
  • amyloid beta-protein (1-42)
  • tau Proteins
  • Threonine