The efficacy of repetition, semantic, and gesture treatments for verb retrieval and use in Broca's aphasia

Abstract

Background: Verb production difficulties are well documented in individuals with aphasia. Yet there remains limited evidence regarding the efficacy of treatments for verb retrieval in these individuals. While previous studies have generally demonstrated positive treatment outcomes in improving single-verb production on confrontation naming tasks, few studies have attempted to examine therapy outcomes in more natural communicative contexts. Aims: This study aimed to evaluate and compare the effects of repetition, semantic, and combined semantic and gesture treatments for verb retrieval and use in individuals with chronic Broca's aphasia. Methods & Procedures: Two individuals with severe and moderate Broca's aphasia participated in this single-participant, multiple-baseline across conditions design. Participant GF presented with mixed levels of verb retrieval deficits and significant apraxia of speech. Participant PF evidenced verb retrieval impairment arising primarily from the output phonological level. A total of 100 action pictures drawn from various sources were balanced for relevant linguistic factors and individual error rates during baseline naming. Treatments were carried out sequentially. Each treatment condition lasted for ten sessions. Semantic treatments involved the production of various features that were semantically associated with the target verb, including associated nouns, and the movement and location characteristics of the target verb. Gesture treatments involved the production of hand and arm movements representative of the target verb. Outcomes & Results: Both participants differed in their response to treatments. GF exhibited increased verb-naming accuracy following repetition-orthographic and combined semantic and gesture treatments; while PF displayed significant increase in naming accuracy following repetition-only and semantic treatment conditions. For both participants, treatments that resulted in significant increase in naming accuracy were shown to be equally efficacious. Both GF and PF also demonstrated increased verb production in narrative and conversation tasks. PF further evidenced improvements in sentence production on a picture description task post-treatment. Conclusions: These findings highlighted the responsiveness to therapy in two individuals with severe and moderate aphasia in the chronic stages. However, there was no significant change in specific lexical, syntactical and morphological linguistic production in conversation. Future research could explore the incorporation of single verb therapy in sentences and/or more natural communicative environments, to further enhance changes at the discourse level.