No abstract

Objective Research shows traumatic brain injury (TBI) survivors underperform compared to healthy comparison participants (HC) on verbal fluency tasks. Verbal fluency is typically comprised of two tasks: letter fluency and semantic fluency. During verbal fluency trials, participants often cluster responses and switch between clusters, which can serve as measures of executive control and organization. Also, research shows that Anglo-Americans (AA) outperformed ethnic minorities on various aspects of cognitive functioning. We examined the relationship between TBI and ethnic diversity on letter fluency, semantic fluency, switching, and clustering. Method The sample included 45 HC adults (21 Hispanics; 24 AA), 33 acute TBI adults (ATBI; 11 Hispanics; 22 AA), and 26 chronic TBI adults (CTBI; 9 Hispanics; 17 AA). Results The groups were well matched, with the exception of gender. ANCOVAs, controlling for gender, revealed HC outperformed ATBI participants on letter fluency, p = .007, ηp2 = .10, letter switching, p = .006, ηp2 = .10, and semantic switching, p = .018, ηp2 = .08. We also found HC outperformed both TBI groups in sematic fluency performances, p = .000, ηp2 = .15. Next, we found Hispanics outperformed AA on letter clustering, p = .003, ηp2 = .09 and semantic clustering, p = .010, ηp2 = .07. Finally, an interaction emerged in letter clustering, p = .044, ηp2 = .06, with the Hispanic ATBI outperforming the AA ATBI group. Conclusion The HC group outperformed both TBI groups only on semantic fluency, but they outperformed the ATBI survivors on letter fluency, letter switching, and semantic switching. Hispanics outperformed AA on letter clustering and semantic clustering, suggesting the use of clustering over switching strategies to provide verbal fluency responses in this group.

Objective We evaluated perceived workload (measured by the NASA Task Load Index; NASA-TLX) as related to Symbol Digit Modalities Test (SDMT) performances in monolingual and bilingual traumatic brain injury (TBI) survivors and healthy comparison participants (HC). Method The sample consisted of 28 TBI survivors (12 monolinguals & 16 bilinguals) and 50 HC (20 monolinguals & 30 bilinguals). SDMT written (SDMT-W) and SDMT oral (SDMT-O) were used to evaluate group differences. Results ANCOVA, controlling for age, revealed that the HC group outperformed the TBI group on SDMT-W, p = .001, and SDMT-O, p = .047. Furthermore, bilinguals outperformed monolinguals on SDMT-W, p = .017. On the NASA-TLX, an interaction emerged on temporal demand rating, p = .023, with TBI bilinguals reporting higher temporal demand on SDMT tasks compared to TBI monolinguals, while the HC monolingual participants reported higher temporal demands ratings compared to HC bilingual participants. Furthermore, monolingual participants showed higher levels of frustration with regard to the SDMT task compared to bilingual participants, p = .029. Conclusion Our data revealed TBI survivors underperformed on both SDMT trials compared to the HC participants. Also, bilingual participants demonstrated better SDMT-W performances compared to monolingual participants. Furthermore, our TBI bilingual sample reported themselves to be more rushed to complete the SDMT compared to monolingual TBI sample, but they were less frustrated. Meanwhile, our HC monolingual sample felt more rushed to complete the SDMT tasks compared to HC bilingual participants, but they were less frustrated. While we observed differences in workload ratings between language groups, it is unclear if language use, and/or other variables are driving these results.

Objective McCaul et al. (2018) recently revised the Dot Counting Test (DCT) cut-off score from ≥17 to 13.80; we evaluated the new cut-off in monolingual and bilingual traumatic brain injury survivors (TBIS) and healthy comparison participants (HCP). Method The sample consisted of 43 acute TBI [ATBI; 23 English monolinguals (EM); 11 English first language bilinguals (EFLB); and 9 English second language bilinguals (ESLB)]; 30 chronic TBI (CTBI; 13 EM; 9 EFLB; 8 ESLB), and 56 HCP (23 EM; 11 EFLB; 22 ESLB). Results An ANCOVA, controlling for age and education, revealed an interaction where ATBI-EFLB had higher E-scores than the other groups and the CTBI-EFLB had lower E-scores than the other groups. Both the conventional and proposed new cut-off (PNC) scores had different failure rates in ATBI (conventional cut-off: 9%; PNC: 28%), CTBI (conventional cut-off: 10%; PNC: 20%), and HCP (conventional cut-off: 11%; PNC: 13%). For language groups, EM (conventional cut-off: 14%; PNC: 22%), EFLB (conventional cut-off: 10%; PNC: 26%), and ESLB (conventional cut-off: 5%; PNC: 10%) demonstrated different failure rates across cut-off scores. Group differences were found with McCaul et al. (2018) cut-off, but not the conventional cut-off score. Also, chi-squared analysis revealed ATBI EFLB and EM had greater failure rates than ATBI ESLB. Conclusion Unfortunately, the new DCT cut-off score resulted in greater failure rates in TBIS. Furthermore, ATBI EM and EFLB were impacted more by the new cut offs than ATBI ESLB who learned English later in life, although the reason for this finding is unclear and requires additional study.

Objective Traumatic brain injury (TBI) survivors often exhibit problems with executive function (EF). Language use can also impact EF test performances. We examined the effects of TBI and bilingualism/monolingualism on several EF tests. Method The sample (N = 94) consisted of 37 healthy controls (19 bilingual; 18 monolingual), 30 acute TBI participants (10 bilingual; 20 monolingual), and 27 chronic TBI participants (16 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury and chronic TBI participants were tested 12 months or more post-injury. Stroop Color-Word (SCW), Delis-Kaplan Executive Function System Letter Fluency (DKEFS-LF), Trail Making Test part B (TMT-B) and a EF global composite (EF-GC) were used to assess EF. All participants passed performance validity testing. 3X2 ANOVAs were conducted to determine the effect of TBI and bilingualism/monolingualism on EF performances. Results Main effects were found between groups (control and TBI groups) on SCW, p = .046, ηp² = .07, TMT-B, p = .042, ηp² = .07, and EF-GC, p = .005, ηp² = .13; the 6-month TBI group performed worse than controls on TMT-B and EF-GC. Main effects were found for bilingualism/ monolingualism on SCW, p = .012, ηp² = .07, and TMT-B, p = .034, ηp² = .05; monolingual participants performed better than bilingual participants. No significant interactions between TBI and language were found. Conclusion The TBI group underperformed on SCW, TMT-B, and EF-GC compared to controls; relative to monolinguals, bilinguals underperformed on the SCW and TMT-B only. In conclusion, our findings seem to suggest that monolinguals have better cognitive flexibility compared to bilinguals that result in better EF performances.