Cross-language interference in bilinguals with neurodegenerative disorders

The aim of the study is to explore the differential effects of neurodegenerative disorders on cross-language interference and facilitation, by comparing the performance in a bilingual Stroop task of Catalan-Spanish bilinguals with different neurodegenerative disorders [Mild Cognitive Impairment (MCI), n = 16; Alzheimer's disease (AD), n = 16; and Parkinson's disease (PD), n = 16)] and healthy controls (n = 14). Interference is the difference in naming latencies between the incongruent (colour words not matching with their ink colour) and control (non-colour words) conditions. Facilitation is the difference between the control and congruent conditions (colour words matching with their ink colour).The results showed that AD and MCI patients, but not PD, showed a larger interference effect than healthy controls. Nevertheless, the patient groups showed the same facilitation effect as healthy controls.The contribution of cortical and subcortical brain areas to cross-language interference suppression is discussed in relation to the type of brain degeneration.