Relationship between discourse and Western Aphasia Battery performance in African Americans with aphasia

There is a need for discourse research with African Americans who have aphasia, highlighted by ethnic group differences in stroke prevalence, and potential ethnic group differences in dialect. Identification of ethnic dialect is critical to differentiate communication changes associated with pathology from normal communicative differences associated with ethnicity. Also, preliminary research on adults with aphasia indicates an uncertain relationship between discourse performance and standardised test performance.

This study was designed to assess: (1) the relationship between performance on a standardised language measure and discourse performance, and (2) the use of ethnic dialect and discourse features, in the narrative productions of African-American adults with moderate aphasia on a variety of discourse tasks.

We investigated the discourse of 12 African Americans with scores in the moderate severity range on the Western Aphasia Battery, Aphasia Quotient (WAB-AQ). Each subject produced a fable retell, a story derived from a picture sequence, two stories derived from single pictures, and a topic-elicited personal narrative of a frightening experience. Analysis consisted of ratings of discourse quality (coherence, reference, and emplotment); a measure of discourse quantity (number of propositions); and a tally of the presence or absence of ethnic dialect and discourse features.

The correlation between WAB-AQ and discourse quality was statistically significant on the picture sequence task and one single-picture task, but not on the other discourse tasks. There was a significant relationship between WAB-AQ and overall quality ratings of coherence, reference, and emplotment. The correlation between WAB-AQ and discourse quantity was not significant for any task, and discourse quality was not significantly correlated with discourse quantity. Ethnic features appeared most often on one single-picture task and the personal narrative. No ethnic dialect features occurred on the fable retell.

These findings suggest the need to supplement standardised assessment of aphasia with assessment of discourse performance, using less structured discourse tasks, such as a personal narrative task. Less structured discourse tasks may also be optimal for eliciting natural ethnic patterns of communication. The lack of relationship between narrative quantity and narrative quality may not generalise to individuals with aphasia that is severe or mild. This study contributes towards development of a discourse assessment tool for culturally and linguistically diverse populations that may supplement information provided by standardised testing.