A-113 Evaluation of a Recognition Trial for the Symbol Digit Modalities Test as a Performance Validity Measure in Monolingual and Bilingual Traumatic Brain Injury Survivors

Abstract

Abstract Objective Research shows that traumatic brain injury (TBI) patients perform worse than healthy comparisons (HC) on the Symbol Digit Modalities Test (SDMT). We evaluated cut-off scores for a newly developed recognition trial of the SDMT as a performance validity assessment in monolingual and bilingual TBI survivors and HC adults. Method The sample consisted of 43 acute TBI (ATBI; 24 monolinguals; 19 bilinguals), 32 chronic TBI (CTBI; 13 monolinguals; 19 bilinguals), and 57 HC (24 monolinguals; 33 bilinguals) participants. All participants received standardized administration of the SDMT. None of the participants displayed motivation for feigning cognitive deficits. Results The HC group outperformed both TBI groups on the demographically adjusted SDMT scores, p = 0.000, ηp2 = 0.24. An interaction emerged in SDMT scores where monolingual ATBI outperformed bilingual ATBI and bilingual CTBI outperformed monolingual CTBI, p = 0.017, ηp2 = 0.06. No differences were found in the SDMT recognition trial. Both Bichlmeier and Boone’s suggested cut-off scores had different failure rates in ATBI (Bichlmeier: 77%; Boone: 37%), CTBI (Bichlmeier: 69%; Boone: 19%), and HC (Bichlmeier: 56%; Boone: 26%). For the monolingual group (Bichlmeier: 66%; Boone: 36%) and the bilingual group (Bichlmeier: 66%; Boone: 21%). Finally, chi-squared analysis revealed monolingual TBI had greater failure rates than the bilingual ATBI. Conclusion Bichlmeier’s proposed cut-off score resulted in greater failure rates in TBI survivors compared to Boone’s suggested cut-off score. Furthermore, monolingual ATBI were influenced more by Bichlmeier’s cut-off score than the bilingual ATBI group, although the reason for this finding is unclear and requires additional study with a larger sample size.