Aphasia severity mediates the relationship between attention and sentence comprehension.

Background: Attention deficits are common after stroke and exacerbate communication challenges in people with aphasia (PWA). Prior studies report mixed associations between attention and language, raising the possibility that these links are explained by aphasia severity. We examined whether alerting, orienting, and executive control attention differ by aphasia severity and whether severity mediates their relationship with sentence comprehension. Methods: Fifty-eight PWA (latent, mild, moderate, severe) and 21 neurotypical controls completed the Attention Network Test, Western Aphasia Battery-Revised, and a sentence-picture matching task. Group differences were tested with ANOVA and linear mixed-effects models. Correlations and structural equation modeling evaluated associations among attention, aphasia severity, and sentence comprehension efficiency. Results: Orienting and executive control differed by aphasia severity, with the severe group performing worse than all others; alerting did not differ across groups. Within group analyses showed that controls and mild aphasia participants demonstrated all three effects, latent aphasia participants showed orienting and executive control effects, while the moderate and severe groups only showed the executive control effect. Stronger orienting and executive control correlated with milder aphasia and more efficient canonical comprehension. Mediation confirmed that orienting influenced canonical and non-canonical comprehension indirectly through aphasia severity; executive control showed trend-level mediation. Alerting attention was unrelated to aphasia severity or comprehension. Conclusions: Orienting and executive control, but not alerting, are closely tied to aphasia severity and indirectly support sentence comprehension. Attentional profiling may enhance individualized rehabilitation planning for PWA.