Naming Performance in Bilinguals with Alzheimer’s Disease and Mild Cognitive Impairment

Introduction. There is consistent evidence of a disadvantage in bilinguals’ speech production compared to monolinguals in healthy individuals, but studies investigating this phenomenon in clinical populations such as Mild Cognitive Impairment (MCI) and Alzheimer’s Disease (AD) are scarce. Given that both clinical groups are characterized by word-finding difficulties, understanding how bilingualism influences speech production in these populations is essential.Methods. Early and highly proficient Catalan–Spanish bilinguals (active bilinguals) were compared to Spanish-dominant speakers with low proficiency in Catalan (passive bilinguals) using a picture-naming task. The study included 58 older adults, 66 patients with AD, and 124 individuals with MCI. Reaction times, accuracy, and error types were collected in the naming task in each individual’s dominant language.Results. First, the results revealed a progressive lexico-semantic impairment from cognitively unimpaired older adults to individuals with MCI and AD. Second, active bilinguals showed greater efficiency in lexical retrieval, reflected in faster processing speed, but this advantage was limited to words sharing orthographic and phonological representations across languages (cognates). Third, error analyses revealed an increased number of semantic errors in the passive bilingual group with MCI and AD, alongside a rise in cross-language intrusions and anomia in the active bilingual group with MCI.Discussion. These findings underscore the impact of second language use on naming performance in MCI and AD. Moreover, they provide insight into the potential mechanisms underlying lexical retrieval differences in bilinguals, including lexico-semantic processing and language control.