Effects of language proficiency and language of the environment on aphasia therapy in a multilingual.

We examined the relative proficiency of four languages (Spanish, German, French, English) of a multilingual speaker with aphasia, JM. JM's self-rated proficiency was consistent with his naming accuracy for nouns and verbs (The Object and Action Naming Battery, Druks & Masterson, 2000) and with his performance on selected subtests of the Bilingual Aphasia Test (Paradis & Libben, 1987). Within and between-language changes were measured following two periods of language treatment, one in a highly-proficient language (Spanish) and one in a less-proficient language (English). The various outcome measures differed in their sensitivity to treatment-associated changes. Cross-language treatment effects were linked to the language of the environment at the time of testing and to relative language proficiency.