Constraint‐induced language therapy for agrammatism: Role of grammaticality constraints

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Background: Aphasia therapy that involves a high weekly intensity, short overall duration, restriction of nonverbal communication, coupled with constraints on verbal complexity, has recently gained momentum (constraint‐induced language therapy, or CILT). The gains have been documented primarily for formal language tests, especially in lexical retrieval, repetition, and comprehension measures. Measures of grammatical well‐formedness, which have greater ecological validity, have not been commonly reported in prior studies. Further, it is as yet unclear if the nature of verbal constraints has any impact on expressive language outcomes, particularly when the primary deficit in verbal production is grammatical inaccuracy (as in the case of agrammatic aphasia). Aims: This study aimed to examine whether constraint‐induced therapy is applicable for individuals with agrammatic aphasia and if the addition of a morphosyntactic constraint would influence expressive language outcomes. Methods & Procedures: In this phase I study a single participant design was used with four chronic agrammatic aphasic individuals who received 24 hours of constraint‐induced therapy over 10 days, as per prior published protocols. Two of these individuals received additional morphosyntactic constraints regarding tense morphology. Formal aphasia tests, Cinderella story narration, and conversational samples were analysed at three time points: pre‐treatment, post‐treatment, and 3‐month follow‐up. Outcomes & Results: While all participants improved on at least some language measures, the overall changes were minimal and not maintained at 3 months. Participants who received morphosyntactic constraints dramatically improved on an elicited morphosyntactic test, but did not respond differently in other severity and discourse measures. Participants with lower initial language severity scores showed quantitatively larger gains after treatment. Conclusions: While constraint‐induced therapy was minimally effective for the agrammatic participants in this study, and addition of a grammaticality constraint did not significantly enhance the functional outcomes, the findings do indicate that initial severity and aphasic deficit patterns may be useful in determining candidacy for constraint‐induced therapy.