Apraxia of speech and phonological errors in the diagnosis of nonfluent/agrammatic and logopenic variants of primary progressive aphasia

J Speech Lang Hear Res. 2012 Oct;55(5):S1562-72. doi: 10.1044/1092-4388(2012/11-0323).


Purpose: The International Consensus Criteria for the diagnosis of primary progressive aphasia (PPA; Gorno-Tempini et al., 2011) propose apraxia of speech (AOS) as 1 of 2 core features of nonfluent/agrammatic PPA and propose phonological errors or absence of motor speech disorder as features of logopenic PPA. We investigated the sensitivity and specificity of AOS and phonological errors as markers for these variants and also investigated the relationship between AOS, phonological errors, and findings on C-labeled Pittsburgh Compound B (PiB)-positron emission tomography (PET) imaging associated with putative Alzheimer-type pathology.

Method: Connected speech and word repetition in 23 people with PPA who underwent PiB-PET imaging were rated for apraxic versus phonological disruption by 1 rater who was blind to diagnosis and by 2 raters who were blind to PiB-PET results.

Results: Apraxic characteristics had high sensitivity for nonfluent/agrammatic PPA, and phonological errors had high sensitivity for logopenic PPA; however, phonological errors showed lower specificity for logopenic PPA. On PiB imaging, 8 of 9 people with predominant AOS returned negative results, whereas participants with no or questionable AOS with and without phonological errors returned positive results.

Conclusions: Attention to AOS and phonological errors may help counter some of the inherent limitations of diagnosis-by-exclusion in the current International Consensus Criteria for diagnosing PPA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / diagnostic imaging
  • Alzheimer Disease / physiopathology
  • Aniline Compounds
  • Aphasia, Broca / diagnostic imaging
  • Aphasia, Broca / physiopathology
  • Apraxias / diagnostic imaging*
  • Apraxias / physiopathology*
  • Carbon Radioisotopes
  • Diagnosis, Differential
  • Female
  • Frontotemporal Dementia / diagnostic imaging
  • Frontotemporal Dementia / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Phonation / physiology*
  • Phonetics*
  • Positron-Emission Tomography / methods
  • Primary Progressive Nonfluent Aphasia / diagnostic imaging*
  • Primary Progressive Nonfluent Aphasia / physiopathology*
  • Psycholinguistics
  • Thiazoles


  • 2-(4'-(methylamino)phenyl)-6-hydroxybenzothiazole
  • Aniline Compounds
  • Carbon Radioisotopes
  • Thiazoles