Word fluency test performance in primary progressive aphasia and primary progressive apraxia of speech

Purpose: This study compared performance on three-word fluency measures among individuals with primary progressive aphasia (PPA) and primary progressive apraxia of speech (PPAOS), and examined the relationship between word fluency and other measures of language and speech. Method: This study included 106 adults with PPA and 30 adults with PPAOS. PPA participants were divided into three clinical subgroups: semantic (svPPA), logopenic (lvPPA), and nonfluent/agrammatic with or without apraxia of speech (nfPPA). Category fluency, letter fluency, and action/verb fluency tasks were administered to all participants. Results: The four clinical groups performed abnormally on the word fluency measures, although not to a degree that represented high sensitivity to their PPA or PPAOS diagnosis. All PPA subgroups produced fewer words compared to individuals with PPAOS on all word fluency measures. Moderate correlations were found between word fluency and aphasia severity and naming performance in some of the clinical groups. Conclusions: Word fluency measures are often challenging for individuals with PPA and PPAOS, but they are not of equal difficulty, with letter fluency being the most difficult. Differences among word fluency tests also vary to some degree as a function of the clinical group in question, with least impairment in PPAOS. However, the findings of this study do not support statistically significant differences in word fluency task performance among the PPA subgroups. Correlations suggest that word fluency performance in PPA is at least partly related to aphasia severity.