General practitioners' approach to malingering in basic military training centres

Medical Evaluation Board Involvement, Non-Credible Cognitive Testing, and Emotional Response Bias in Concussed Service Members

Introduction

Military Service Members (SMs) with post-concussive symptoms are commonly referred for further evaluation and possible treatment to Department of Defense Traumatic Brain Injury Clinics where neuropsychological screening/evaluations are being conducted. Understudied to date, the base rates of noncredible task engagement/performance validity testing (PVT) during cognitive screening/evaluations in military settings appears to be high. The current study objectives are to: (1) examine the base rates of noncredible PVTs of SMs undergoing routine clinical or Medical Evaluation Board (MEB) related workups using multiple objective performance-based indicators; (2) determine whether involvement in MEB is associated with PVT or symptom exaggeration/symptom validity testing (SVT) results; (3) elucidate which psychiatric symptoms are associated with noncredible PVT performances; and (4) determine whether MEB participation moderates the relationship between psychological symptom exaggeration and whether or not SM goes on to demonstrate PVTs failures - or vice versa.

Materials and Methods

Retrospective study of 71 consecutive military concussion cases drawn from a DoD TBI Clinic neuropsychology clinic database. As part of neuropsychological evaluations, patients completed several objective performance-based PVTs and SVT.

Results

Mean (SD) age of SMs was 36.0 (9.5), ranging from 19-59, and 93% of the sample was male. The self-identified ethnicity resulted in the following percentages: 62% Non-Hispanic White, 22.5% African American, and 15.5% Hispanic or Latino. The majority of the sample (97%) was Active Duty Army and 51% were involved in the MEB at the time of evaluation. About one-third (35.9%) of routine clinical patients demonstrated failure on one or more PVT indicators (12.8% failed 2) while PVT failure rates amongst MEB patients ranged from 15.6% to 37.5% (i.e., failed 2 or 1 PVTs, respectively). Base rates of failures on one or more PVT did not differ between routine clinical versus MEB patients (p = 0.94). MEB involvement was not associated with increased emotional symptom response bias as compared to routine clinical patients. PVT failures were positively correlated with somatization, anxiety, depressive symptoms, suspicious and hostility, atypical perceptions/alienation/subjective cognitive difficulties, borderline personality traits/features, and penchant for aggression in addition to symptom over-endorsement/exaggeration. No differences between routine clinical and MEB patients across other SVT indicators were found. MEB status did not moderate the relationship between any of the SVTs.

Conclusion

Study results are broadly consistent with the prior published studies that documented low to moderately high base rates of noncredible task engagement during neuropsychological evaluations in military and veteran settings. Results are in contrast to prior studies that have suggested involvement in MEB is associated with increased likelihood of poor PVT performances. This is the first to show that MEB involvement did not enhance/strengthen the association between PVT performances and evidence of SVTs. Consistent with prior studies, these results do highlight that the same SMs who fail PVTs also tend to be the ones who go on to endorse a myriad of psychiatric symptoms and proclivities. Implications of variable or poor task engagement during routine clinical and MEB neuropsychological evaluation in military settings on treatment and disposition planning cannot be overstated.