B-69 The Effect of Bilingualism on Symbol Digit Modalities Test Performance in Traumatic Brain Injury Survivors and Healthy Adults

Objective Traumatic brain injury (TBI) survivors exhibit cognitive deficits. Language factors can also influence neurocognitive performance. We examined the effects of TBI and bilingualism/monolingualism on a test of attention and cognitive speed (i.e., Symbol Digit Modalities Test; SDMT). Method The sample (N = 98) consisted of 37 controls (19 bilingual; 18 monolingual), 34 acute TBI participants (12 bilingual; 22 monolingual), and 27 chronic TBI participants (16 bilingual; 11 monolingual). Acute TBI participants were tested 6 months post-injury; chronic TBI participants were tested 12 months or more post-injury. All participants passed performance validity testing. 3X2 ANOVAs were conducted to determine the effect of TBI and language on SDMT written and oral performance. Results A main effect was found between groups (control and TBI groups) on SDMT written, p < .001, ηp² = .19 and SDMT oral p < .001, ηp² = .16. Pairwise comparisons revealed a difference between the control group and TBI groups, with TBI groups performing worse. A main effect for bilingualism/monolingualism was not found; interaction effects emerged between TBI and bilingualism/monolingualism on SDMT written, p < .05, ηp² = .07 and SDMT oral p < .05, ηp² = .07. Conclusion TBI groups performed worse than controls on the SDMT. Relative to monolinguals with TBI, our findings suggest better cognitive recovery of verbal attention and cognitive speed in bilingual TBI participants.