Effect of treatment for bilingual individuals with aphasia: A systematic review of the evidence

Language proficiency in bilingualism, and hence bilingual aphasia, is a multifaceted phenomenon: influenced by variables such as age of onset, literacy, usage patterns, and emotional valence. Although the majority of the world and growing US population is bilingual, relatively little is known about the best practices for language therapy in bilingual aphasia. This systematic review was undertaken to examine three crucial questions faced by speech-language pathologists during clinical decision making: outcomes when language therapy is provided in the secondary (less-dominant) language (L2), extent of cross-language transfer (CLT) and variables that influence CLT, and outcomes when language therapy is mediated by a language broker. Data from 14 studies (N 1⁄4 45 aphasic individuals) indicate that treatment in L2 leads to positive outcomes (akin to L1 treatment); CLT was found to occur in most studies, especially when L1 was the language of treatment. Although limited by the methodological quality of included studies, this systematic review shows positive findings for unilingual aphasia treatment and CLT. Implications for clinical practice, models of language representation in bilinguals, and future research directions are discussed. 2010 Elsevier Ltd. All rights reserved. vidence-based Practice in Communication Disorders, American Speech, Rockville, MD 20850, USA. Tel.: þ1 301 296 8742; fax: þ1 301 296 8588.