Identifying the components of a successful spoken naming therapy: a meta-analysis of word-finding interventions for adults with aphasia

ABSTRACT

Background: Spoken word retrieval therapy forms an integral part of aphasia therapy. Due to the range of therapy options and variations, drawing clear-cut conclusions from the evidence base can be challenging.

Aims: This paper consolidates recent findings (2008–2018), pertinent to spoken word-finding interventions. Specifically, we are interested in aphasia interventions: (1) that target single-word spoken naming; (2) whose participants are adults with acquired naming impairments after a stroke; and (3) whose treatment approach focusses on the use of language forms (i.e., semantics, phonology, and orthography). The over-arching objective is to determine the important therapy components underpinning successful single-word naming treatments.

Methods and Procedures: A systematic literature search was conducted. This led to the compilation of a large-scale dataset (n=222 participants from 32 papers), with the heterogenous interventions dissected into their “active” therapy components. A detailed framework (“RITA”: (1) Regimen; (2) Item(s); (3) Technique(s); and (4) Application of technique(s) with their Adjuncts) was designed to organise these “active therapy ingredients”. Using random forest, we identified the crucial components responsible for the successful naming of treated and untreated items, respectively, at short-term and maintenance periods.

Outcomes and Results: The role of the written form as therapeutic cues, presented either as a whole word or part-word, emerged to be a consistent and robust predictor, across the outcomes. Semantic tasks were useful in the successful naming of untreated items.

Conclusions: Clinicians should consider using written prompts as part of spoken naming therapy. It is possible that the use of orthography underlies the success of multi-component techniques. Other clinical implications (e.g., homework, treatment intensity) are also discussed. In addition, we propose a comprehensive “RITA” framework, which summarises the “active” therapy components. “RITA” (available as a template in Appendix 3) is useful for clinicians and researchers as a guide to unpack language interventions. Furthermore, the paper highlights the strengths of a well-established method, random forest, as a valuable statistical tool to move aphasia research forward. Overall, the study refines our understanding of spoken naming treatment for those with aphasia, specifically individuals with word-finding deficits. Importantly, through the use of a robust statistical approach and an original framework designed to lay out language therapy components, the paper adds new clarity to the evidence base.

KEYWORDS:

• Anomia rehabilitation
• treatment for word retrieval difficulty
• oral naming language disorder recovery
• stroke
• machine learning

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. The PubMed search was performed by the first author on 08 March 2019.

2. It is beyond the scope of this paper to include all reviews published between 2008 and 2018. This is not intended to be a systematic report of existing reviews of single-word naming therapies. Rather, Table 1 represents the main efforts, based on the following criteria. These reviews: (1) Evaluated the efficacies between different interventions, i.e., not just devoted to evaluating one type of therapy; and (2) Provided numerical analysis of the studies they included, to support their main points. It is common in aphasia research for the reviews to include single-case experimental designs and/or randomised controlled trials (RCTs).

3. Technically, researchers could just run say subgroup analyses with just studies looking at Semantic Feature Analyses (SFAs), and obtain the pooled effect. This finding is however quite limited, as it only tells us in isolation, whether SFA is effective, but fails to help us compare against other interventions. Additionally, it treats SFA as a package, and does not recognise it has shared similarities with other types of therapies (e.g., feedback, written semantic cues). In truth, any of these shared components could be the genuine cause behind its proposed efficacy.

4. Unfortunately, in the Cochrane review by Brady et al. (2016), the heterogeneity index, I² statistic, was not reported.

5. https://www.stat.berkeley.edu/~breiman/RandomForests/cc_home.htm

6. A rudimentary count revealed that for the journal “Aphasiology”, single-case or case-series intervention studies made up 20% of the original articles published in 2018.

7. Although not stated in the analyses, for each database, we created scatterplots between the median rankings across 20 databases and the individual database’s rankings to ensure that in each of them, the relationship between the two types of rankings was monotonic. All scatterplots showed a linear distribution in the increasing direction. Monotonicity is an assumption in Kendall’s Tau-b.

8. To clarify, we are referring to the lack of studies that investigate the exclusive role of orthography, i.e., provide only the written form in treatment and is not accompanied by other cues (e.g., phonology). Orthographic cues are often explored in aphasia rehabilitation literature in the context of other techniques/cues, but it also means we cannot disambiguate the role of orthography from these accompaniments. We would also like to mention that the figures in Tables 6 to 8 do not contradict our statement on the rarity of research dedicated to the sole investigation of orthographic cues, compared to other approaches. In these tables, the numbers reflect the number of participants, not the number of studies. Snell et al. (2010), who provided both phonological and orthographic cues, was a case series of 13 participants. Rider et al. (2008), who used SFA, had three participants. This is not surprising because of the resource demands (e.g., time) necessitated when conducting SFA, which may explain the smaller sample sizes. Nevertheless, all these suggest that many participants were involved in research that examined written cues in the wider context of other techniques/cues. These numbers further emphasise how fewer participants (in our case, zero participants across the 32 papers) undertook a therapy research that relied purely on orthography.

9. Croot et al. (2015) is mentioned to make an illustration on the therapy technique. In their paper, the two participants were diagnosed with primary progressive aphasia, so their data are not included in this meta-analysis.

Additional information

Funding

This research was supported by the University College London scholarships [Graduate Research Scholarship and Overseas Research Scholarship] awarded to the first author.