Quantitative application of the primary progressive aphasia consensus criteria

Objective:To determine how well the consensus criteria could classify subjects with primary progressive aphasia (PPA) using a quantitative speech and language battery that matches the test descriptions provided by the consensus criteria.Methods:A total of 105 participants with a neurodegenerative speech and language disorder were prospectively recruited and underwent neurologic, neuropsychological, and speech and language testing and MRI in this case-control study. Twenty-one participants with apraxia of speech without aphasia served as controls. Select tests from the speech and language battery were chosen for application of consensus criteria and cutoffs were employed to determine syndromic classification. Hierarchical cluster analysis was used to examine participants who could not be classified.Results:Of the 84 participants, 58 (69%) could be classified as agrammatic (27%), semantic (7%), or logopenic (35%) variants of PPA. The remaining 31% of participants could not be classified. Of the unclassifiable participants, 2 clusters were identified. The speech and language profile of the first cluster resembled mild logopenic PPA and the second cluster semantic PPA. Gray matter patterns of loss of these 2 clusters of unclassified participants also resembled mild logopenic and semantic variants.Conclusions:Quantitative application of consensus PPA criteria yields the 3 syndromic variants but leaves a large proportion unclassified. Therefore, the current consensus criteria need to be modified in order to improve sensitivity.