Phonemic Fluency and Rhyme Production in People with Aphasic Word Retrieval Disorders: Sub-Lexical Written Language...

In everyday communication, word retrieval is semantically driven. A similar processing mechanism can be assumed for category fluency tasks. In contrast, in phonemic fluency tasks or rhyme production, the retrieval process must be based on the word form. In phonemic fluency, executive and language functions have been discussed as influencing this specific retrieval mechanism. In addition, studies of adults with developmental dyslexia and non-literate individuals have shown that deficits in written language processing are associated with poorer performance in phonemic fluency; a relationship that is not evident for category fluency. In people with aphasia (PWA), there is a lack of research on the possible relationship between written language skills and word form based word retrieval performance, although PWA often have acquired dyslexia/dysgraphia. There is also a paucity of data on possible effects on rhyme production.

The aim of the present study was to investigate the effects of written language skills, word retrieval performance, aphasia severity and executive function on phonemic fluency, rhyme production and category fluency. It is hypothesised that phonemic fluency and rhyme production are associated with written language skills, while this is not assumed for category fluency. Word retrieval performance, aphasia severity and executive functions could have an impact on all three tasks.

The study was conducted with 19 PWA (13f, 6m), showing predominantly post-semantic word retrieval disorders. The assessment included the following tasks: phonemic fluency, rhyme production, category fluency, reading and writing of nonwords (sub-lexical written language), reading and writing of unregular words (lexical written language), oral naming in the Boston Naming Test (word retrieval), Token Test (aphasia severity) and two visual-spatial tasks, spatial 2-back (executive function: updating) and antisaccade (executive function: inhibition). Descriptive analyses included correct responses and errors. In a second step, data were analysed by using hierarchical regression analyses.

For both phonemic fluency and rhyme production, reading/writing of nonwords showed the strongest explanatory power. In contrast, for category fluency, the strongest predictor was oral naming performance in the Boston Naming Test.

The results of the current study indicate that sub-lexical written language abilities are associated with phonemic fluency and rhyme production performance. In light of these results, it must be critically discussed whether phonemic fluency and rhyme production are appropriate tasks in the diagnosis and therapy of post-semantic word retrieval disorders, particularly in PWA with acquired dyslexia/dysgraphia.

What is already known on this subject So far, it has been discussed that language functions, e.g., confrontation naming performance or vocabulary size, and executive functions have an impact on phonemic fluency in people with aphasia (PWA). In addition, studies with people with developmental dyslexia and non-literate people have shown that phonemic fluency performance is strongly influenced by segmental written language skills. What this paper adds to the existing knowledge The present study has shown that in PWA with post-semantic word retrieval disorders, segmental written language skills, i.e., reading/writing of nonwords, are associated with their performance in phonemic fluency and rhyme production. In contrast, performance in category fluency showed a relationship with spoken word retrieval abilities as measured by confrontation naming. What are the potential or actual clinical implications for this work? At least for PWA with dyslexia/dysgraphia, word form-based tasks such as phonemic fluency and rhyme production may not be appropriate for assessing or treating word retrieval disorders, as performance on these tasks, which rely on phonological strategies, appears to be related to deficits in segmental written language skills. Alternatively, tasks that also require semantic references may be more appropriate.