Clinical Neuropsychology of Bilingual Mexican American Adults: Effect of Language Proficiency and Dominance.

Objective: To assess the association between language proficiency and absolute dominance on language versus visual-perceptual formatted and executive versus delayed memory neuropsychological measures in bilingual adults.

Methods: Data from 55 bilingual, conversationally fluent, neurologically intact, Mexican American, consecutive, adults tested in separate sessions in Spanish and English in a counterbalanced order were analyzed. Age, years of education, self-reported language proficiency, Woodcock-Muñoz Language Survey-Revised (WMLS-R) picture vocabulary measures of language proficiency, and dominance (absolute Spanish-English WMLS-R difference scores) were correlated with 11 measures from La Batería Neuropsicólogica en Español and its original English language tests.

Results: Self-reported and WMLS-R measures of language proficiency were significantly correlated in each language. Absolute language dominance was not significantly associated with any Spanish or English neuropsychological raw score. The WMLS-R language proficiency, but not age or years of education, was significantly correlated with language-formatted neuropsychological measures of California Verbal Learning Test delayed free recall number of words (both languages), letter fluency (both languages), delayed story memory (in English), and Stroop interference (Spanish). Linear regression models using age, years of education, and WMLS-R picture vocabulary scores as predictors were significant for all these measures excepting the last. The WMLS-R language proficiency was not significantly associated with raw scores on any visual-perceptual formatted measure.

Conclusions: Monolingual neuropsychological test norms for language-formatted tests likely overestimate bilingual Mexican Americans' performance.