Cognitive control, word retrieval and bilingual aphasia: Is there a relationship?

It is proposed that successful word retrieval involves lateral inhibition of lexical competitors, and suppression of the non-target language in bilingual speakers. Thus cognitive control is crucial for word production. Given that word retrieval difficulty is a hallmark feature of aphasia, the relationship between word retrieval and cognitive control in aphasia has not been sufficiently explored. This study examined whether persons with aphasia show 1) evidence of a cognitive control deficit, 2) bilingual status interacts with cognitive control deficit in persons with aphasia, and (3) a relationship between measures of word naming and cognitive control. Thirty-eight persons with aphasia were administered a task of cognitive control (Stroop color-word task) and two word production tasks (picture naming and category fluency). We found weakened cognitive control in aphasia relative to age-matched neurologically healthy adults. A bilingual advantage in cognitive control was found in neurologically healthy adults and in one group of bilingual speakers with aphasia, but not the other group. Word retrieval in persons with aphasia was not correlated with Stroop task performance. These findings show that cognitive control performance (as measured by the Stroop task) is compromised in persons with aphasia, irrespective of bilingual status. There was a bilingual advantage in two out of three groups, showing a general support for the bilingual inhibitory control advantage (BICA) hypothesis.