Treating verbs in aphasia: exploring the impact of therapy at the single word and sentence levels

Abstract

Background: In recent years there has been significant interest in the differential processing of nouns and verbs in people with aphasia, but more limited consideration about whether the differences have implications for therapy. It remains unclear whether verbs can be treated in a similar way to nouns or should be treated using approaches that recognize the relationship between verb retrieval and sentence production. Aims: This paper reviews studies focusing on therapy for spoken verb retrieval, considering the impact of therapy on treated and untreated verbs, sentence production and connected speech. It explores whether there are differential gains across therapy paradigms and whether verbs respond to therapy in the same way as nouns. Method & Procedures: Studies were identified using a systematic search. A total of 26 studies were reviewed and classified under four headings: (1) studies that treated verbs in a single‐word context, (2) studies that compared treatment for nouns and verbs, (3) studies that treated verbs in a sentence context, and (4) studies that treated verb retrieval and argument structure. Main Contribution: Findings from the review demonstrate that verb therapy, irrespective of whether verbs are treated within a single‐word or sentence context, is effective in improving the retrieval of treated verbs, but with limited generalization to untreated verbs. Verbs respond very similarly to nouns when treated using the same techniques, but improving verb retrieval may be harder to achieve than improving noun retrieval. The impact on sentence production is more varied. The gains in sentence production are discussed in relation to the different therapy types, the rationale for therapy and the presence of co‐occurring sentence difficulties. Conclusions: The review highlights the need for more systematic evaluation of different types of verb therapy, measuring the impact of therapy on verb retrieval, sentence production and connected speech. Only through the judicious assessment and monitoring of change across different contexts will an understanding of how verbs respond to therapy be developed and what generalization patterns can be predicted. This will lead to increased confidence in the selection of therapy approaches for people with verb difficulties in aphasia.

Effect of Verb Network Strengthening Treatment (VNeST) in Persons With Aphasia: Extension and Replication of Previous Findings

“…Some improvements to sentence production were reported (Bastiaanse et al, 2006;Edwards & Tucker, 2006;Links et al, 2010;McCann & Doleman, 2011), with improvement to connected speech in a few participants (Bastiaanse et al, 2006;Edwards & Tucker, 2006;Links et al, 2010). Although the improvements to sentence production and connected speech are encouraging, the gains observed in these studies were primarily structural and/or grammatical (Webster & Whitworth, 2012), not lexical.…”

“…Presumably, improvement beyond trained networks occurred, at least in part, because of increased lexical retrieval. However, adequate sentence frame construction abilities are important for integrating improved lexical retrieval into sentences (see Webster & Whitworth, 2012). It is conceivable that VNeST tasks, such as agent and patient retrieval around a trained verb and reading aloud the agent-verb-patient responses in canonical order, may have strengthened both lexical retrieval and basic sentence construction abilities.…”

“…In addition, more generalized improvement of lexical retrieval abilities for single words and sentences unrelated to treatment and discourse is hypothesized with VNeST because of the wide range of concepts produced in treatment , though individual participant variables, including exacerbating cognitive and language impairments, could certainly affect potential improvement (see Lambon Ralph, Snell, Fillingham, Conroy, & Sage, 2010;Webster & Whitworth, 2012). Investigation of outcome measures across a hierarchy of lexical retrieval tasks may allow for insight into the extent of possible generalization as well as patterns of improvement within and across participants.…”

“…As discussed in Webster and Whitworth (2012), the degree of improvement to argument structure depends on whether argument structure is lexically specified. If it is, improvement will be restricted to treated verbs, but if it is not, improvement in sentence production could be more widespread.…”

“…A subset of these studies (as described by Webster & Whitworth, 2012) focused primarily on sentence structure, syntax, and/or morphosyntax (e.g., Bastiaanse, Hurkmans, & Links, 2006;Conroy, Sage, & Lambon Ralph, 2009;Edwards & Tucker, 2006;Links, Hurkmans, & Bastiaanse, 2010;McCann & Doleman, 2011;Raymer & Kohen, 2006). Trained tasks included sentence completion and production and sentence production cuing hierarchies.…”