title: Apraxia profile differentiates behavioural variant frontotemporal from Alzheimer's dementia in mild disease stages.
abstract: OBJECTIVE
  Despite refined criteria for behavioural variant frontotemporal dementia (bvFTD), its differentiation from Alzheimer's dementia (AD) remains difficult at early clinical presentation. Apraxia is not considered as a supportive feature for the diagnosis of bvFTD, but for AD. However, only few studies have quantified praxis disturbances in mild disease stages and their specificity for AD compared with bvFTD remains indistinct. We explore apraxia in bvFTD and investigate the differential validity of apraxia screening tests to distinguish between AD, bvFTD and healthy controls (HC).
  
  
  METHODS
  We compared composite apraxia scores assessed with standardised neuropsychological screening tests as well as performance in praxis subdomains in patients who fulfil current clinical criteria for AD (N=20), bvFTD (N=20), and in HC (N=20).
  
  
  RESULTS
  Composite scores of apraxia screening tests provided high diagnostic accuracy for detecting mild stages of both neurodegenerative disorders compared with HC (sensitivity: 75-95%; specificity: 70-90%). Both patient groups showed pronounced impairments in limb praxis, especially in imitation of hand and finger postures (bvFTD: 71.7%; AD: 55.5%; HC: 86.7%) and pantomime of object use (bvFTD: 88.6%; AD: 81.4%; HC: 97.5%). Beyond that, patients with bvFTD displayed a unique profile of deficits for imitating face postures (bvFTD: 69%; AD: 88%; HC: 95.5%).
  
  
  CONCLUSIONS
  Praxis disturbances are important but under-represented diagnostic features in mild stages of AD and bvFTD. Apraxia screening tests are easily applicable diagnostic tools, which may support clinical diagnoses of both neurodegenerative diseases. The analysis of individual apraxia profiles can effectively facilitate differential diagnosis of AD and bvFTD.
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Johnen
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Amelie
authors.initials: A
authors.lastname: Tokaj
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Kirschner
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Heinz
authors.initials: H
authors.lastname: Wiendl
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Gero
authors.initials: G
authors.lastname: Lueg
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Duning
authors.affiliation: Department of Neurology, University Hospital Münster, Münster, Germany.
authors.forename: Hubertus
authors.initials: H
authors.lastname: Lohmann
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000503:physiopathology; D001259:Ataxia / Q000175:diagnosis / Q000209:etiology*; D003937:Diagnosis, Differential; D005260:Female; D057180:Frontotemporal Dementia / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D012680:Sensitivity and Specificity
keywords: ALZHEIMER'S DISEASE; APRAXIA; BEHAVIOURAL DISORDER; DEMENTIA; NEUROPSYCHOLOGY