Response inhibition in Veterans with a history of mild traumatic brain injury: The role of self-reported complaints in objective performance.

INTRODUCTION

Although objective deficits in response inhibition (RI) have been detected in civilians with mild traumatic brain injury (mTBI), it remains unclear whether objective RI is worse in military Veterans with mTBI despite the prevalence of self-reported disinhibition. Assessing RI in Veterans is critical due to their unique characteristics, including combat and blast exposure, in addition to the prevalence of psychiatric comorbidity. Therefore, the aims of this study were to (1) examine RI performance in Veterans with mTBI compared to non-mTBI Veterans and (2) compare RI performance in well-defined subgroups of mTBI Veterans with and without self-reported complaints of disinhibition to non-mTBI Veterans.

METHOD: 53 mTBI Veterans and 37 non-mTBI Veterans completed a Go/No-Go RI task and measures of self-reported disinhibition (Frontal Systems Behavior Scale) and psychiatric symptoms. ANCOVAs covarying for mood and demographics compared RI performances of the non-mTBI Veterans to (1) the total sample of mTBI Veterans (n= 53) and to (2) mTBI Veterans with elevated (t-score ≥ 60; mTBI-SubjDis; n= 23) and low (t-score < 60; mTBI-NoSubjDis; n= 30) levels of self-reported disinhibition.

RESULTS

There were no significant differences in RI between the mTBI group as a whole and the non-mTBI Veterans group. However, when Veterans with mTBI were divided into groups by clinically-significant concern about their disinhibition, the mTBI-SubjDis group demonstrated significantly worse RI than the mTBI-NoSubjDis and non-mTBI Veteran groups. No significant differences in RI performance were observed between the mTBI-NoSubjDis and non-mTBI Veteran groups.

CONCLUSIONS

Results indicate that mTBI Veterans with elevated levels of self-reported disinhibition show diminished performance on objective measures of RI, independent of mood. Findings highlight the unique contribution of subjective complaints on executive functioning in mTBI, and they underscore the importance of assessing cognitive complaints in order to identify those most at risk for poor-long term outcomes.