Aphasia severity mediates the relationship between attention and sentence comprehension.

Background: Prior studies report mixed associations between attention and language in people with aphasia (PWA), raising the possibility that their relationship may be influenced by another factor, such as aphasia severity. We examined this possibility by testing whether alerting, orienting, and executive control attention vary as a function of aphasia severity and whether severity statistically mediates their association with sentence comprehension. Methods: In a retrospective analysis combining data from two prior studies, 58 individuals with aphasia, ranging from latent to severe, and 21 neurotypical controls completed the Attention Network Test and a sentence-picture matching task. Group differences in attention were assessed using ANOVAs, and linear mixed-effects models evaluated the presence of each attentional effect within groups. Correlations and structural equation modeling examined associations among attention, aphasia severity, and sentence comprehension. Results: All three attention types were present in the control and mild aphasia groups; only orienting and executive control were observed in the latent group, and only executive control in the moderate and severe groups. Orienting and executive control performance declined with increasing aphasia severity, whereas alerting did not differ by severity. Stronger orienting and executive control were associated with more efficient sentence comprehension, but this relationship was statistically mediated by aphasia severity. Conclusions: These findings suggest that associations between domain-general attention and sentence comprehension are best understood within the broader context of aphasia severity and highlight the need for future research clarifying the directionality of this relationship.