The Dysexecutive questionnaire (DEX), a 20-item ecological measure used by patients (DEX-S) or significant others (DEX-SO) to assess dysexecutive syndrome, often complements performance-based executive functions (EF) tests. Previous studies highlighted its internal consistency, score variability across samples, weak DEX-S correlations with EF tests, but strong associations with self-assessments of anxiety/depression. This study examined DEX-S and DEX-SO scores from the PariS-TBI study, analyzing data from 76 severe TBI participants and 40 proxies assessed 8-years postinjury compared to matched healthy controls.

DEX scores in the control group followed a normal distribution, but severe TBI participants reported significantly higher percentages of very low DEX scores and significantly higher percentages of extremely high scores in both self-reports and proxy-reports. Strong correlations were found between DEX-S and self-reported anxiety/depression (rho=0.65, p<0.001).

These findings suggest a possible lack of self-awareness in some TBI participants, a probable tendency of some TBI-proxies to underestimate EF difficulties, and the presence of EF difficulties in the TBI group compared to controls. The tendency among some TBI participants and proxies to respond to the DEX questions based on their positive or negative valence (presence of a "valence bias"), rather than specific content, potentially elucidates our results and prior published DEX findings.