Training flexibility in fixed expressions in non-fluent aphasia: A case series report

Many speakers with non-fluent aphasia (NFA) are able to produce some well-formed word combinations such as 'I like it' or 'I don't know', although they may not use variations such as 'He likes it' or 'I don't know that person'. This suggests that these utterances represent fixed forms.

This case series investigation explored the impact of a novel intervention aimed at enhancing the connected speech of individuals with NFA. The intervention, motivated by usage-based principles, involved filling open slots in semi-fixed sentence frames.

Five participants with NFA completed a 6-week intervention programme. The intervention trained participants to insert a range of different lexical items into the open slots of high-frequency phrases such as 'I like it' to enable more productive sentences (e.g., 'they like flowers'). The outcomes and acceptability were examined: The primary outcome measure focused on changes in connected narrative, and the availability of trained constructions (e.g., 'I like it') was explored through a story completion test. Two baseline measures of behaviour were taken prior to intervention, and outcomes assessed immediately after intervention and at a 6-week maintenance assessment.

A pre-/post-treatment comparison of connected speech measures showed evidence of enhanced connected speech for two of the five participants (P2 and P5). An analysis of story completion test scores revealed positive change for two participants (P1 and P2). Findings were mixed with regard to baseline stability of outcome measures and post-intervention stability of language changes. The intervention was acceptable to all participants.

While this pilot study yielded promising findings with regard to the intervention's acceptability and increased connected speech for some participants, the findings were mixed across the sample of five participants. This research helps inform hypotheses and selection criteria for future studies.

What is already known on the subject Despite difficulties producing grammatically correct sentences, many speakers with aphasia are able to produce well-formed utterances, often representing familiar expressions such as 'I don't know' and 'I like it'. In usage-based Construction Grammar (CxG) theories, familiar utterances are assumed to be processed as one unit and are therefore more resilient to brain damage. CxG assumes that residual utterances such as 'I like it' map onto more abstract sentence frames (e.g., '[REFERENT] like-TENSE [THING]'). What this paper adds to existing knowledge Sentence therapy, informed by CxG principles, is novel in aphasiology, and usage-based interventions need to be evaluated with regard to their impact on language processing at the connected speech level. This case series report explores the acceptability and outcomes of a usage-based sentence therapy. We also introduce and explore the value of an automated, frequency-based analysis tool for evaluating connected speech outcomes in aphasia therapy. What are the potential or actual clinical implications of this work? The findings inform further development of usage-based aphasia interventions targeting word combinations.