Poster C2, Wednesday, August 21, 2019, 10:45 am – 12:30 pm, Restaurant Hall
Verbal executive function tests capture language and control processes in chronic post stroke aphasia
Rahel Schumacher1, Ajay D. Halai1, Matthew A. Lambon Ralph1;1MRC Cognition and Brain Sciences Unit, University of Cambridge
There is growing awareness that aphasia following a stroke can include deficits in other cognitive functions, for instance in executive functions, and that these are predictive of certain aspects of language function, recovery and rehabilitation. A variety of tests measuring different aspects of executive functions have been developed, but many commonly used tests contain linguistic stimuli and require speech output. Therefore, they are usually not administered in patients with aphasia. However, given that the interrelations between language and executive functions remain a matter of debate, and that non-aphasic dysexecutive patients’ performance in semantic tests parallels that of patients with semantic aphasia, aphasic patients’ performance on verbal executive tests might provide valuable insights, both from a theoretical and a clinical perspective. We administered three commonly used verbal executive tests (Letter & Category Fluency, Hayling, Stroop) to a sample of up to 32 patients with varying aphasia severity. Their performance in these tests and in a broad range of background tests regarding their language and nonverbal cognitive functions, as well as information about their lesion volume and location were taken into account to elucidate: 1) if verbal executive tests measure anything beyond the language impairment in this patient group; 2) how performance in such tests relates to performance in language tests and nonverbal cognitive functions; 3) the neural correlates associated with performance on verbal executive tests. Separate principal component analyses of the performance in the three verbal executive tests showed a remarkably stable pattern of dissociation between core language demands and more general control abilities for the Hayling and Stroop tasks. This dissociation was further corroborated by significant correlations between factor scores on the language components with patients’ overall verbal impairment, as well as significant correlations of the factor scores on the control components with patients’ nonverbal impairment. The components underlying the Fluency tasks showed a less clear-cut separation of a language component but yielded also two main components to do with word generation and switching abilities. Importantly, the generation component was associated with patients’ overall verbal as well as nonverbal impairment. Furthermore, lesion analyses revealed distinguishable clusters for the two components for each test. Our findings thus extend our clinical and theoretical understanding of dysfunctions beyond language in patients with aphasia.
Themes: Control, Selection, and Executive Processes, Disorders: Acquired
Method: Behavioral