The methodological quality of short-term/working memory treatments in poststroke aphasia: A systematic review: A systematic review

Purpose: The aims of this systematic review are to providea critical overview of short-term memory (STM) andworking memory (WM) treatments in stroke aphasia andto systematically evaluate the internal and external validityof STM/WM treatments. A systematic search was conducted in February2014 and then updated in December 2016 using 13 electronicdatabases. We provided descriptive characteristics of theincluded studies and assessed their methodological qualityusing the Risk of Bias in N-of-1 Trials quantitative scale (Tateet al., 2015), which was completed by 2 independent raters. The systematic search and inclusion/exclusionprocedure yielded 17 single-case or case-series studieswith 37 participants for inclusion. Nine studies targetedauditory STM consisting of repetition and/or recognitiontasks, whereas 8 targeted attention and WM, such asattention process training including n-back tasks withshapes and clock faces as well as mental math tasks. Interms of their methodological quality, quality scores onthe Risk of Bias in N-of-1 Trials scale ranged from 4 to 17(M = 9.5) on a 0–30 scale, indicating a high risk of bias inthe reviewed studies. Effects of treatment were mostfrequently assessed on STM, WM, and spoken languagecomprehension. Transfer effects on communication andmemory in activities of daily living were tested in only5 studies. Conclusions: Methodological limitations of the reviewedstudies make it difficult, at present, to draw firm conclusionsabout the effects of STM/WM treatments in poststroke aphasia.Further studies with more rigorous methodology and strongerexperimental control are needed to determine the beneficialeffects of this type of intervention. To understand theunderlying mechanisms of STM/WM treatment effects andhow they relate to language functioning, a careful choiceof outcome measures and specific hypotheses aboutpotential improvements on these measures are required.Future studies need to include outcome measures ofmemory functioning in everyday life and psychosocialfunctioning more generally to demonstrate the ecologicalvalidity of STM and WM treatments.