Treatment of verb tense morphology in agrammatic aphasia: A systematic review

This paper aims to review the literature on the therapeutic approaches employed for the treatment of verb tense inflection in individuals with agrammatic aphasia and the reported outcomes on language production and verb tense inflection. All studies on the treatment of verb tense inflection were found by searching Cochrane library, ISI Web of Knowledge, Google Scholar, Pubmed, and Scopus until December 2020, with the combination of these keywords, ‘aphasia, verb, morphology, tense, therapy, treatment, rehabilitation’. All studies (single-case or group design) on the treatment of verb tense inflection in individuals with acquired aphasia were reviewed. Data were synthesized descriptively through tables to allow the facilitated comparison of the studies. The methodology of the reviewed studies was assessed using single-case experimental designs (SCED) scale. An adaptation of the Cochrane Collaboration's risk of bias (RoB) tool was employed to evaluate the risk of bias (RoB) in the reviewed studies. A total of 14 studies were selected and reviewed. The results of the reviewed studies demonstrated that the remediation of tense morphology production in individuals with agrammatic aphasia is effective and verb tense marking can be improved by therapies that specifically target this disorder. This review highlights the need for a more systematic investigation of different types of treatments for tense marking. Also, more detailed information about the treatment of regular vs irregular verbs are required to elucidate the potential efficiency of these two verb types in the treatment of tense inflection. Overall, regarding the theoretical and clinical aspects, the number of studies that specifically target tense morphology are growing and based on the positive potential of these treatments, they could be suitable for the rehabilitation of people with aphasia, especially those with agrammatism.