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

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.