Word retrieval following mild TBI: Implications for categorical deficits

Abstract

Background: Theories on the organisation and structure of semantic knowledge of nouns and verbs have been based on findings with aphasic patients with focal lesions. Populations with diffuse lesions, such as mild traumatic brain injury (MTBI), may offer additional information relative to lexical access of nouns and verbs. Aims: The purpose of this study was to investigate possible dissociation between noun and verb retrieval after MTBI using the Test of Adolescent Adult Word Finding (TAWF). Methods & Procedures: Two groups, 10 MTBI and 10 non‐brain‐damaged (NBD) persons, who had normal vision and hearing, and no history of developmental disabilities, previous head injury, or substance abuse, were participants. Criteria for MTBI included: loss of consciousness <30 minutes and/or PTA<24 hours, GCS 13–15, and negative CT scan. The experimental task was the TAWF, focusing on differences in accuracy and response time for noun and verb naming. Outcomes & Results: Paired sample t‐tests comparing nouns and verbs on accuracy and response time revealed no significant differences for the MTBI group; for the NBD group, there were significant differences for response time only. One‐tailed independent sample t‐tests revealed significant group differences for accuracy and response time on combined nouns and only response time for verbs. Paired sample t‐tests revealed significant differences for naming living and nonliving items only for the MTBI group. Conclusions: No significant accuracy differences were found for either group between nouns and verbs. However, the NBD group named nouns significantly faster than verbs, whereas the MTBI group showed no significant difference. The MTBI group was significantly slower and less accurate than the NBD group for noun naming but only significantly slower for verbs. The MTBI group exhibited higher accuracy in naming living items as compared to nonliving. Therefore, response times appeared to be more sensitive than accuracy in identifying group differences.