Does brain volume loss predict cognitive and narrative discourse performance following traumatic brain injury?

Purpose: In this study, the authors investigated the relationship between brain volume loss and performance on cognitive measures, including working memory, immediate memory, executive functions, and intelligence, and a narrative discourse production task. An underlying goal was to examine the prognostic potential of a brain lesion metric for discourse outcomes. It was hypothesized that brain volume loss would correlate with and predict cognitive and narrative discourse measures and have prognostic value for discourse outcomes. Method: One hundred sixty-seven individuals with penetrating head injury participated. Correlational and regression analyses were performed for the percentages of total brain and hemispheric volume loss and scores on 4 cognitive measures (WMS-III Working Memory and Immediate Memory primary indexes, D-KEFS Sorting Test, and WAIS-III Full Scale IQ) and 7 narrative discourse measures (T-units, grammatical complexity, cohesion, local and global coherence, story completeness, and story grammar). Results: The volumetric measures had significant small-to-moderate correlations with all cognitive measures but only one significant correlation with the discourse measures. Findings from regression analyses were analogous but revealed several models that approached significance. Conclusion: Findings suggest that an overall measure of brain damage may be more predictive of general cognitive status than of narrative discourse ability. Atrophy measures in specific brain regions may be more informative.