Baseline executive control ability and its relationship to language therapy improvements in post-stroke aphasia: a systematic review

ABSTRACT

Purpose: To review current evidence on the relationship between executive control (EC) and post-treatment language gains in adults with post-stroke aphasia.

Method: Electronic databases (CINAHL, Cochrane Trials, Embase, MEDLINE, MEDLINE-in-Process and PsycINFO) were systematically searched (year 2000 – present). Abstracts and full-text articles were reviewed by two independent raters against pre-specified criteria: original research with N > 2; at least 90% adults with stroke, all undergoing treatment for acquired aphasia; pre-treatment EC abilities were compared to language gains post-treatment across studies. Critical appraisal was conducted using the Cochrane group and Single-Case Experimental Design (SCED) methods. Data were extracted and summarised descriptively.

Results: Search results yielded 2272 unique citations; ultimately 15 studies were accepted for review. Both pre-treatment EC and language abilities appear to be important indicators of treatment success, especially in moderate-severe aphasia. This relationship emerged when EC was measured using specific (e.g., divided attention), as opposed to broad (e.g., reasoning) tasks, and primarily when naming therapy was administered; intensive constraint-induced therapy did not correlate with treatment success.

Conclusions: EC is a promising prognostic variable regarding language recovery, but further research is required using a-priori declared theoretical EC models, along with properly powered samples, standardised EC tasks and treatment protocols.

KEYWORDS:

• Stroke
• aphasia
• executive control
• executive functioning
• language treatment
• systematic review

Acknowledgments

We thank Jessica Babineau, a librarian at Toronto Rehabilitation Institute – University Health Network, for assistance with the literature search protocol.

Disclosure Statement

No potential conflict of interest was reported by the authors.

ORCID

Tijana Simic http://orcid.org/0000-0001-6638-6514

Elizabeth Rochon http://orcid.org/0000-0001-5521-0513

Elissa Greco http://orcid.org/0000-0001-7504-3169

Rosemary Martino http://orcid.org/0000-0002-3298-7714

Notes

1. Three additional studies met all inclusion criteria for this review (Fillingham et al., 2005a, 2005b; Nicholas, Sinotte, & Helm-Estabrooks, 2005). The participants presented by Fillingham and colleagues (2005a, 2005b), however, were subsets of the participants presented in Fillingham et al., 2006, a study already included in this review and aggregated in Lambon-Ralph and colleagues (2010), as described in footnote two. Similarly, the participants presented in Nicholas, Sinotte, and Helm-Estabrooks (2005) represented a subset of those presented in Nicholas et al., 2011, therefore we chose to exclude the earlier study in this case.

2. Lambon Ralph et al. (2010) amalgamated data from four previously published single-subject design studies (Conroy, Sage, & Lambon Ralph, 2009a; Fillingham et al., 2006; Sage et al., 2011; Snell et al., 2010). One of those studies is represented individually here (Fillingham et al., 2006). The inclusion of the Fillingham et al., 2006 study was determined by discussion and consensus amongst the authors. Given that this study met all inclusion criteria and presented a more homogeneous subset of the Lambon Ralph et al., 2010 data (i.e., the participants in this study only received one block of therapy, as it was the first in a series of studies), it was deemed an informative addition to the review.

Additional information

Funding

This research was supported by a Heart and Stroke Foundation of Ontario (#NA7015) grant to Elizabeth Rochon and a Heart and Stroke Foundation of Canada, Canadian Partnership for Stroke Recovery award to Tijana Simic. Rosemary Martino received support from her Canada Research Chair (Tier II) in Swallowing Disorders.