Discourse after traumatic brain injury (TBI) in Japanese speakers has not been sufficiently investigated, and it remains unclear whether multilevel discourse-analysis procedures devised for Western languages apply to Japanese. Moreover, the specific indices that best capture TBI-related discourse impairments have yet to be fully established. Therefore, our study aimed to apply an established Western framework to a group of native Japanese speakers with TBI to compare their discourse features with those of a group of healthy controls and identify indicators of post-TBI discourse. These participants completed a comic-strip explanation task; their narratives were analyzed at the microstructural, macrostructural, and superstructural levels. Discourse features were compared between the TBI and control groups. Logistic regression was conducted to identify discourse predictors of TBI, and the neuropsychological test scores of the TBI group correlated with the discourse indices. The TBI group performed worse than controls at every discourse level. Reduced global coherence and a smaller total number of clauses independently predicted TBI status. In addition, the global coherence correlated with all neuropsychological measures except the forward digit span, indicating dependence on diverse cognitive functions. These findings show that Japanese speakers exhibit impairments at multiple discourse levels following TBI, similar to Western populations. In particular, the reduced global coherence appears to be a primary factor contributing to disorganized narratives and difficulties in maintaining thematic continuity. These results support the cross-linguistic applicability of multilevel discourse analysis and underscore its importance for guiding language rehabilitation following TBI. • Japanese patients with TBI show impairments at multiple discourse levels. • Reduced global coherence reflects impaired narrative organization. • Reduced global coherence contributes to difficulties in thematic continuity. • Multilevel discourse analysis can guide language rehabilitation after TBI.
Fujiwara et al. (Tue,) studied this question.