Methodological challenges in assessment of cognition following mild head injury: response to Malojcic et al. 2008

PREFACE to what traditional neuropsychological assessment got wrong about mild traumatic brain injury. A four-part opinion review

This Preface overviews a four-part opinion series on the role of tradtional neuropsychological tests in evaluating mild traumatic brain injury (mTBI), juxtaposed to all of the progress that has occurred with advanced neuroimaging and allied technologies. The four areas of review and critique are: I. Neuropathology; II: Limitations in Test Development, Statistical and Psychometric Issues; III. Implications of Advanced Neuroimaging Findings inn the Neuropsychological Assessment of the mTBI Patient, and IV: Clinical Applications and Future Directions. The example is made that since their inception in the early to mid-20th Century, traditional neuropsychological measures mostly have remained invariant, have been used as omnibus measures for assessing all types of neurological and neuropsychiatric conditions, and were never specifically designed to asses the effects of mTBI. Extensive discussion is provided across all four parts concerning the limits of traditional neuropsychological methods, especially in the absences of any integration with advanced neuroimaging and biomarker findings. Part IV provides an outline for future research and clinical application in the development of novel neuropsychological assessment mesasures specific to mTBI.

Performance validity and symptom validity tests: Are they measuring different constructs?

OBJECTIVE

To evaluate the relationships among performance validity, symptom validity, symptom self-report, and objective cognitive testing.

METHOD

Combat Veterans (N = 338) completed a neurocognitive assessment battery and several self-report symptom measures assessing depression, posttraumatic stress disorder (PTSD) symptoms, sleep quality, pain interference, and neurobehavioral complaints. All participants also completed two performance validity tests (PVTs) and one stand-alone symptom validity test (SVT) along with two embedded SVTs.

RESULTS

Results of an exploratory factor analysis revealed a three-factor solution: performance validity, cognitive performance, and symptom report (SVTs loaded on the third factor). Results of t tests demonstrated that participants who failed PVTs displayed significantly more severe symptoms and significantly worse performance on most measures of neurocognitive functioning compared to those who passed. Participants who failed a stand-alone SVT also reported significantly more severe symptomatology on all symptom report measures, but the pattern of cognitive performance differed based on the selected SVT cutoff. Multiple linear regressions revealed that both SVT and PVT failure explained unique variance in symptom report, but only PVT failure significantly predicted cognitive performance.

CONCLUSIONS

Performance and symptom validity tests measure distinct but related constructs. SVTs and PVTs are significantly related to both cognitive performance and symptom report; however, the relationship between symptom validity and symptom report is strongest. SVTs are also differentially related to cognitive performance and symptom report based on the utilized cutoff score. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Neuroimaging biomarkers in mild traumatic brain injury (mTBI)

Reviewed herein are contemporary neuroimaging methods that detect abnormalities associated with mild traumatic brain injury (mTBI). Despite advances in demonstrating underlying neuropathology in a subset of individuals who sustain mTBI, considerable disagreement persists in neuropsychology about mTBI outcome and metrics for evaluation. This review outlines a thesis for the select use of sensitive neuroimaging methods as potential biomarkers of brain injury recognizing that the majority of individuals who sustain an mTBI recover without neuroimaging signs or neuropsychological sequelae detected with methods currently applied. Magnetic resonance imaging (MRI) provides several measures that could serve as mTBI biomarkers including the detection of hemosiderin and white matter abnormalities, assessment of white matter integrity derived from diffusion tensor imaging (DTI), and quantitative measures that directly assess neuroanatomy. Improved prediction of neuropsychological outcomes in mTBI may be achieved with the use of targeted neuroimaging markers.

Symptom validity testing, effort, and neuropsychological assessment

Symptom validity testing (SVT) has become a major theme of contemporary neuropsychological research. However, many issues about the meaning and interpretation of SVT findings will require the best in research design and methods to more precisely characterize what SVT tasks measure and how SVT test findings are to be used in neuropsychological assessment. Major clinical and research issues are overviewed including the use of the “effort” term to connote validity of SVT performance, the use of cut-scores, the absence of lesion-localization studies in SVT research, neuropsychiatric status and SVT performance and the rigor of SVT research designs. Case studies that demonstrate critical issues involving SVT interpretation are presented.