The effect of a sentence comprehension treatment on discourse comprehension in aphasia

While it is well understood that individuals with aphasia have difficulty with discourse comprehension, very few studies have examined the nature of discourse comprehension deficits in aphasia and the potential for improvement in discourse comprehension after rehabilitation. To address the first goal, we previously developed the Test of Syntactic Effects on Discourse Comprehension (TSEDC), which provides a measure of the extent to which a participant's sentence comprehension ability aids in comprehending passages (Levy et al., 2012).

The goal of this study was to examine the effect of a sentence comprehension treatment on the TSEDC to assess if training participants to understand sentences of different syntactic complexity would improve their ability to understand passages that vary by their level of syntactic complexity.

Forty participants with aphasia received sentence comprehension treatment using one of two syntactic comprehension tasks: object manipulation (OM) or sentence to picture matching (SPM). The dependent measure was improved sentence comprehension of one sentence type in one task-related protocol, with the order of task and structure counterbalanced across participants. Before and after treatment, participants also completed a self-paced auditory story comprehension task which involved 9 passages that contained either semantically reversible canonical sentences (simple passages) or semantically reversible noncanonical sentences (complex passages). At the end of each passage, participants were asked explicit or implicit questions about the story. Accuracy and reaction times were measured for each patient for each story before and after treatment.

Analysis of the treatment data revealed that participants improved in their ability to understand trained sentences (both in terms of effect size and percent change on trained structure), irrespective of whether the trained task was SPM or OM. There was no significant relationship between treatment improvements on the SPM/OM treatment (even when the task targeted in treatment was controlled for) and changes in performance on the TSEDC. Also, there was no significant improvement in TSEDC accuracy after treatment, even when various aspects of the narrative passages, including passage complexity (simple/complex), the nature of sentence type (semantically constrained/semantically reversible) and the nature of questions asked (explicit or implicit) were accounted for.

Inherent differences between the sentence comprehension treatment and the TSEDC may have precluded generalization.