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Research paper
Logopenic aphasia in Alzheimer's disease: clinical variant or clinical feature?
  1. Samrah Ahmed1,
  2. Celeste A de Jager2,
  3. Anne-Marie F Haigh2,
  4. Peter Garrard1
  1. 1Stroke and Dementia Research Centre, St George's, University of London, London, UK
  2. 2Oxford Project to Investigate Memory and Ageing (OPTIMA), Nuffield Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
  1. Correspondence to Dr P Garrard, Stroke and Dementia Research Centre, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK; pgarrard{at}sgul.ac.uk

Abstract

Background Primary progressive aphasia (PPA) is a clinical syndrome characterised by progressive decline in components of the language system. Recent evidence suggests that the logopenic/phonological (LPA) variant is a reliable in vivo marker of Alzheimer related pathology. The aim of this study was to determine if patients with clinically typical early stage Alzheimer's disease (AD) display a characteristic language disorder that resembles LPA, or if LPA is a clinical manifestation of an atypical form of AD.

Methods Spoken language samples were obtained using the Cookie Theft picture description task from 18 post mortem confirmed cases of AD, where speech samples were taken at the first point of clinical diagnosis, and 18 post mortem confirmed healthy controls. Spoken samples were transcribed from tape recordings and analysed using the scoring system described by Wilson et al.

Results Group comparisons between normal controls and AD patients showed no significant overall differences. Individual review of the linguistic variables compared with the PPA variants showed that a third of patients had normal language (n=6). The remainder showed varied patterns of linguistic impairment. In the majority of the affected group, the most salient feature was a reduction in one or more measures of syntactic complexity. One patient's deficit was comparable to that found in LPA.

Conclusions The impairment found in clinically typical early stage AD did not correspond consistently to the linguistic profiles described in any of the sub-syndromes of PPA. The only reliably distinguishing feature was a reduction across a range of syntactic complexity measures. The findings suggest that LPA represents an atypical clinical presentation of AD rather than a common clinical feature of typical AD.

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Footnotes

  • Funding This work was supported by UK Medical Research Council research grant No G0801370, awarded to PG and CAdJ.

  • Competing interests None.

  • Ethics approval The study was approved by the Southampton and West Hampshire research ethics committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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