Prognostic Factors
language impairment, aphasia, language deficits
Our second aim investigated the association between aphasia severity, age, TPO, education, cognitive reserve, and naming outcomes. We focused our analyses on these particular factors as they have been subject to similar examinations in prior research, without firm conclusions as to how they can be used to inform clinical prognostication. Our findings revealed that aphasia severity, as measured by the WAB-AQ, emerged as a dominating predictor in each model. Age was found to be a negative predictor of change in naming from baseline to follow-up assessments at 1 month and 6 months posttherapy. TPO was only found to be predictive of change in naming performance at 6 months posttherapy. Cognitive reserve, as measured by the Matrix Reasoning subtest of the WAIS, and years of education were not associated with a treatment-induced change in naming at any assessment time point.
The nature of the relationship between severity and treated recovery has, nonetheless, been debated (e.g., 


Cognitive reserve, like residual language function, depends largely on the integrity of remaining intact brain tissue (e.g., 
In summary, we observed immediate improvement in naming performance after SLT and retention of language gains 6 months after treatment in a representative sample of persons with aphasia. Our results indicate that individuals with relatively mild language impairment (i.e., WAB-AQ ≥ 51) are more likely to respond favorably to impairment-based naming therapy compared to those with more severe language deficits. Younger individuals are more likely to retain therapy-induced language gains in the long term compared to older individuals, and shorter TPO may similarly confer positive long-term prognosis. Of equal importance, we found that the very severely affected group (i.e., WAB-AQ ≤ 25) and, to a lesser extent, the severely affected group (i.e., WAB-AQ = 26–50) did not demonstrate a significant improvement in naming performance after therapy, suggesting that an alternative form of treatment might need to be considered for this group. These findings are consistent with the recent notion that greater focus should be placed on counseling and alternative and augmentative and alternative approaches in severe aphasia, whereas restoring language function should be a primary aim in moderate and mild aphasia (This study represents the largest systematic examination of the direct association between five commonly considered prognostic factors and response to therapy. Our results certainly suggest that it is possible to enhance clinical prognostication in aphasia, and future research should aim to determine in greater detail the extent to which therapy response can be informed based on baseline aphasia severity, age, and TPO. Looking further ahead, a prognostic model based on these factors may (a) serve as a basis to test the unique predictive value of other prognostic factors (e.g., lesion information or language deficit profiles) and (b) be utilized to examine differences related to therapy parameters such as treatment concentration or focus, intensity or dosage, and therapy modality.