Motor dysfunction profiles in traumatic brain injury and postconcussion syndrome

Using the Grooved Pegboard Test as an Embedded Validity Indicator in a Mixed Neuropsychiatric Sample with Varying Cognitive Impairment: Cross-Validation Problems

Embedded validity indicators (EVIs) derived from motor tests have received less empirical attention than those derived from tests of other neuropsychological abilities, particularly memory. Preliminary evidence suggests that the Grooved Pegboard Test (GPB) may function as an EVI, but existing studies were largely conducted using simulators and population samples without cognitive impairment. In this study we aimed to evaluate the GPB's classification accuracy as an EVI among a mixed clinical neuropsychiatric sample with and without cognitive impairment. This cross-sectional study comprised 223 patients clinically referred for neuropsychological testing. GPB raw and T-scores for both dominant and nondominant hands were examined as EVIs. A known-groups design, based on ≤1 failure on a battery of validated, independent criterion PVTs, showed that GPB performance differed significantly by validity group. Within the valid group, receiver operating characteristic curve analyses revealed that only the dominant hand raw score displayed acceptable classification accuracy for detecting invalid performance (area under curve [AUC] = .72), with an optimal cut-score of ≥106 seconds (33% sensitivity/88% specificity). All other scores had marginally lower classification accuracy (AUCs = .65-.68) for differentiating valid from invalid performers. Therefore, the GPB demonstrated limited utility as an EVI in a clinical sample containing patients with bona fide cognitive impairment.

Cross-validation and initial investigation of two abbreviated methods of the finger tapping test

The Finger Tapping Test (FTT) is a widely utilized measure to assess lateralized motor speed and dexterity. The current study sought to cross-validate an abbreviated version of the FTT (i.e., M of Trials 3-5) and to evaluate a novel abbreviated method (i.e., M of three trials within five taps of each other; "3 within 5") to examine their respective effectiveness as a predictor of full-score performance based on a traditional administration procedure. The results showed that the abbreviated methods accurately predicted the full-test score, and any statistically significant differences that emerged were small based on effect size analysis and unlikely to be clinically meaningful. These findings were consistent across genders, among older adults, and among individuals displaying significant inter-trial tapping variability and thus requiring lengthier administration time. Classification accuracy statistics for the detection of impairment and performance validity status were high for both abbreviated methods. The results support two valid options for shortening the duration of the FTT. Both methods, used independently or in combination, are compatible with traditional administration procedures.

Validation of grooved pegboard cutoffs as an additional embedded measure of performance validity

OBJECTIVE

Using embedded performance validity (PVT) comparisons, Erdodi et al. suggested that Grooved Pegboard (GPB) T-score cutoffs for either hand (≤ 29) or both hands (≤ 31) could be used as additional embedded PVTs. The current study evaluated the relationship between these proposed cutoff scores and established PVTs (Medical Symptom Validity Test [MSVT]; Non-Verbal Medical Symptom Validity Test [NV-MSVT], and Reliable Digit Span [RDS]).

METHOD

Participants (N = 178) were predominately Caucasian (84%) males (79%) with a mean age and education of 41 (SD = 11.7) and 15.8 years (SD = 2.3), respectively. Participants were stratified as "passing" or "failing" the GPBviaErdodi's proposed criteria. "Failures" on the MSVT, NV-MSVT, and RDS were based on conventional recommendations.

RESULTS

Moderate correlations between GPB classification and a condition of interest (COI; i.e. at least two failures on reference PVTs) were observed for dominant (χ² (1, n = 178) = 34.72, ϕ = .44, p < .001), non-dominant (χ² (1, n = 178) = 16.46, ϕ = .30, p = .001), and both hand conditions (χ² (1, n = 178) = 32.48, ϕ = .43, p < .001). Sensitivity, specificity, and predictive power were generally higher than Erdodi et al.'s initial findings.

CONCLUSION

These findingsprovide supportfor the clinical utility of the GPB as an additional embedded PVT. More specifically, dominant and both hand cutoffs were found to be more robust measures ofnon-genuine performance in those without motor deficits. While promising, sensitivity continues to be low; therefore, it is ill-advised to use the GPB as a sole measure of -performance validity.

Incidence and characteristics of physical disabilities in patients with postconcussion syndromefollowing mTBI

This study aimed to examine the incidence and characteristics of physical disabilities in patients with postconcussion syndrome (PCS) after a mild traumatic brain injury (mTBI). Of 203 patients diagnosed with PCS after mTBI, 10 patients with definite physical disabilities (worse than moderate disability on the Glasgow outcome scale [GOS], <4 points and inability to walk independently on the Functional Ambulation Category [FAC], <3 points) were enrolled. Ten of the 203 patients included in the analysis based on prespecified inclusion criteria were further evaluated. Seven patients had moderate disability on the GOS, whereas the remaining 3 showed severe disability. On the Modified Barthel Index, 5 patients were moderately dependent, and 2 patients were severely dependent. By the Motricity Index, 9 patients showed mild quadriparesis, and 1 had mild hemiparesis. All 10 patients could grasp-release their fingers as per the Modified Brunnstrom Classification. By contrast, 7 patients required verbal supervision for independent gait by the FAC, and the remaining 3 patients needed intermittent support from 1 person for independent gait. Approximately 5% of patients with PCS after mTBI had a definite physical disability, and most of these patients showed mild quadriparesis. These results suggest that a definite physical disability can occur in patients with PCS after mTBI.

An Australian study on feigned mTBI using the Inventory of Problems - 29 (IOP-29), its Memory Module (IOP-M), and the Rey Fifteen Item Test (FIT)

We investigated the classification accuracy of the Inventory of Problems - 29 (IOP-29), its newly developed memory module (IOP-M) and the Fifteen Item Test (FIT) in an Australian community sample (N = 275). One third of the participants (n = 93) were asked to respond honestly, two thirds were instructed to feign mild TBI. Half of the feigners (n = 90) were coached to avoid detection by not exaggerating, half were not (n = 92). All measures successfully discriminated between honest responders and feigners, with large effect sizes (d ≥ 1.96). The effect size for the IOP-29 (d ≥ 4.90), however, was about two-to-three times larger than those produced by the IOP-M and FIT. Also noteworthy, the IOP-29 and IOP-M showed excellent sensitivity (>90% the former, > 80% the latter), in both the coached and uncoached feigning conditions, at perfect specificity. Instead, the sensitivity of the FIT was 71.7% within the uncoached simulator group and 53.3% within the coached simulator group, at a nearly perfect specificity of 98.9%. These findings suggest that the validity of the IOP-29 and IOP-M should generalize to Australian examinees and that the IOP-29 and IOP-M likely outperform the FIT in the detection of feigned mTBI.

Neurophysiological abnormalities in individuals with persistent post-concussion symptoms

Concussion injury results in a rapid onset of transient neurological impairment that can resolve quickly, or sometimes evolve over time, but usually resolve within seven to 10 days. However, a small but noticeable cohort (~10%) of individuals continues to experience persistent lingering effects, particularly fatigue, recognized as post-concussion symptoms (PCS). This study explored neurophysiological mechanisms in people with persistent PCS. Studies involved using self-report post-concussion fatigue scale, transcranial magnetic stimulation (TMS) and somatosensory stimulation in those with diagnosed PCS (n = 20; 36.1 ± 14.0 yr., 4 female; mean time post-concussion 15.4 ± 7.6 months) to fully recovered individuals (n = 20; 33.8 ± 6.6 yr., 2 female; post-concussion 12.9 ± 6.6 months) and healthy controls (n = 20; 37.7 ± 8.0 yr., 3 female). PCS participants demonstrated a significantly higher self-report fatigue (score: PCS 20.2 [95% CI 17.4-22.9], Recovered 6.2 [3.1-9.3], Control 2.75 [0.6-4.8]). PCS participants showed a worsening of reaction time (F_2,57 = 4.214; p = 0.020) and increased reaction time variability (F_2,57 = 5.505; p = 0.007). Somatosensory differences were observed for amplitude discrimination (F_2,57 = 5.166; p = 0.009), temporal order judgment (F_2,57 = 4.606; p = 0.014) and duration discrimination (F_2,57 = 6.081; p = 0.004). Increased intracortical inhibition in TMS single pulse suprathreshold stimulation (110%: F_2,57 = 6.842; p = 0.002; 130%: F_2,57 = 4.900; p = 0.011; 150%: F_2,57 = 4.638; p = 0.014; 170%: F_2,57 = 9.845; p < 0.001) and paired pulse protocols was also seen (SICI: F_2,57 = 23.390; p < 0.001, and LICI: F_2,57 = 21.603; p < 0.001). Using non-invasive stimulation techniques, this novel study showed increased cortical inhibition and compromised central information processing, suggesting neural mechanisms underpinning ongoing fatigue, allowing for potential clinical rehabilitation strategies.

Prolonged Repetitive Head Trauma Induces a Singular Chronic Traumatic Encephalopathy-Like Pathology in White Matter Despite Transient Behavioral Abnormalities

Repetitive mild traumatic brain injury (rmTBI), resulting from insults caused by an external mechanical force that disrupts normal brain function, has been linked to the development of neurodegenerative diseases, such as chronic traumatic encephalopathy and Alzheimer disease; however, neither the severity nor frequency of head injury required to trigger adverse behavioral outcomes is well understood. In this study, the administration of 30 head impacts using two different weights to lightly anesthetized, completely unrestrained mice established a paradigm that simulates the highly repetitive nature of sports- and military-related head injury. As the number of head impacts increases, the time to recover consciousness diminishes; however, both the sensorimotor function and behavioral outcomes of impacted mice evolve during the ensuing weeks. Postmortem analyses reveal robust Alzheimer disease and chronic traumatic encephalopathy-like conditions that manifest in a singular manner throughout the white matter concomitant with evidence of chronic oligodendrogenesis. Our data suggest that latency to recover the righting reflex may be an inadequate measure of injury severity and imply that exposure to repeated head impacts may mask the severity of an underlying and developing neuropathologic condition that does not manifest itself until long after head collisions cease. In addition, our data indicate that there is a cumulative and dose-dependent effect of repetitive head impacts that induces the neurobehavioral and neuropathologic outcomes seen in humans with a history of rmTBI.

Movement disorders and motor impairments following repeated head trauma: A systematic review of the literature 1990-2015

BACKGROUND

There is increasing attention on the long-term sequelae following multiple concussions and traumatic brain injury (TBI) in later life. The majority of the research has focused on long-term cognitive impairments and behavioural changes. Despite being researched and reported, long-term motor dysfunction and movement disorders as a consequence of concussions and TBI have not received due consideration.

REVIEW

This study used a systematic review and qualitative analysis that focused on two key areas: (1) identified movement disorders in individuals with a reported history of repeated concussions or repeated mild-to-moderate TBIs; and (2) identified motor impairments in individuals with a history of repeated concussions or repeated mild-to-moderate TBIs. Fourteen studies investigating long-term movement disorders or motor impairments as a result of repeated concussions or TBI met the selection criteria. Study ratings were moderate-to-high; therefore, evidence was strong enough to conclude that repeated concussions or repeated mild/moderate TBIs did affect the motor system.

CONCLUSION

The evidence in this systematic review highlights the need for future studies to include motor outcomes along with cognitive and behavioural outcomes when assessing the long-term effects of repeated concussions or repeated mild/moderate TBIs.

Lipopolysaccharide preconditioning prevents acceleration of kindling epileptogenesis induced by traumatic brain injury

10-20% of symptomatic epilepsies are post-traumatic. We examined effect of LPS preconditioning on epileptogenesis after controlled cortical impact (CCI). LPS (0.01, 0.1 and 0.5 mg/kg) was injected i.p. to rats 5 days before induction of CCI to parieto-temporal cortex. Kindling started 24h after CCI by i.p. injection of 30 mg/kg of pentylenetetrazole every other day until manifestation of 3 consecutive generalized seizures. CCI injury accelerated the rate of kindled seizures acquisition. LPS (0.1 and 0.5 mg/kg) prevented the acceleration of kindling. LPS preconditioning significantly decreased IL-1β and TNF-α over-expression and the number of damaged neurons in the hippocampus of traumatic rats.

Assessment of response bias in neurocognitive evaluations

BACKGROUND

In clinical neuropsychological practice, assessment of response validity (e.g., effort, over-reporting, under-reporting) is an essential component of the assessment process. By contrast, other health care professionals, including those in neurorehabilitation settings, often omit assessment of this topic from their evaluations or only rely on subjective impressions.

OBJECTIVE

To provide the first comprehensive review of response validity assessment in the neurorehabilitation literature, including why the topic is often avoided, what methods are commonly used, and how to decrease false positives.

METHODS

A literature review and documentation of personal experience and perspectives was used to review this topic.

RESULTS

There is a well-established literature on the necessity and utility of assessing response validity, particularly in patients who have external incentives to embellish their presentation or to under-report symptoms. There are many reasons why non-neuropsychologists typically avoid assessment of this topic. This poses a significant problem, particularly when patients exaggerate or malinger, because it can lead to misdiagnosis and it risks increasing the cost of healthcare by performing unnecessary tests and treatments, unfair distribution of disability/compensation resources, and a reduced access to these and other health resources by patients who genuinely need them.

CONCLUSIONS

There is a significant need for non-neuropsychologists to develop and incorporate symptom and performance validity assessments in clinical evaluations, including those in neurorehabilitation settings.

Test validity and performance validity: considerations in providing a framework for development of an ability-focused neuropsychological test battery

Literature on test validity and performance validity is reviewed to propose a framework for specification of an ability-focused battery (AFB). Factor analysis supports six domains of ability: first, verbal symbolic; secondly, visuoperceptual and visuospatial judgment and problem solving; thirdly, sensorimotor skills; fourthly, attention/working memory; fifthly, processing speed; finally, learning and memory (which can be divided into verbal and visual subdomains). The AFB should include at least three measures for each of the six domains, selected based on various criteria for validity including sensitivity to presence of disorder, sensitivity to severity of disorder, correlation with important activities of daily living, and containing embedded/derived measures of performance validity. Criterion groups should include moderate and severe traumatic brain injury, and Alzheimer's disease. Validation groups should also include patients with left and right hemisphere stroke, to determine measures sensitive to lateralized cognitive impairment and so that the moderating effects of auditory comprehension impairment and neglect can be analyzed on AFB measures.

Controlled-cortical impact reduces volitional forelimb strength in rats

Traumatic brain injury (TBI) is one of the largest health problems in the United States and affects both cognitive and motor function. Although weakness is common in TBI patients, few studies have demonstrated a reduction in strength in models of brain injury. We have developed a behavioral method to measure volitional forelimb strength and quantify forelimb weakness following traumatic brain injury. In this paper, we report the ability of the isometric pull task to measure both acute and chronic impairments in forelimb motor function following a controlled cortical impact (CCI) in rodents. Following CCI, volitional forelimb strength is reduced by 36% and remains significantly reduced after 6 weeks of post-lesion training. We also show that CCI results in impairment of multiple additional measures of forelimb function for several weeks post-injury.

Neuropsychological differential diagnosis of mild traumatic brain injury

The diagnosis and evaluation of mild traumatic brain injury (mTBI) is reviewed from the perspective of meta-analyses of neuropsychological outcome, showing full recovery from a single, uncomplicated mTBI by 90 days post-trauma. Persons with history of complicated mTBI characterized by day-of-injury computed tomography or magnetic resonance imaging abnormalities, and those who have suffered prior mTBIs may or may not show evidence of complete recovery similar to that experienced by persons suffering a single, uncomplicated mTBI. Persistent post-concussion syndrome (PCS) is considered as a somatoform presentation, influenced by the non-specificity of PCS symptoms which commonly occur in non-TBI samples and co-vary as a function of general life stress, and psychological factors including symptom expectation, depression and anxiety. A model is presented for forensic evaluation of the individual mTBI case, which involves open-ended interview, followed by structured interview, record review, and detailed neuropsychological testing. Differential diagnosis includes consideration of other neurologic and psychiatric disorders, symptom expectation, diagnosis threat, developmental disorders, and malingering.

Performance validity and symptom validity in neuropsychological assessment

Failure to evaluate the validity of an examinee's neuropsychological test performance can alter prediction of external criteria in research investigations, and in the individual case, result in inaccurate conclusions about the degree of impairment resulting from neurological disease or injury. The terms performance validity referring to validity of test performance (PVT), and symptom validity referring to validity of symptom report (SVT), are suggested to replace less descriptive terms such as effort or response bias. Research is reviewed demonstrating strong diagnostic discrimination for PVTs and SVTs, with a particular emphasis on minimizing false positive errors, facilitated by identifying performance patterns or levels of performance that are atypical for bona fide neurologic disorder. It is further shown that false positive errors decrease, with a corresponding increase in the positive probability of malingering, when multiple independent indicators are required for diagnosis. The rigor of PVT and SVT research design is related to a high degree of reproducibility of results, and large effect sizes of d = 1.0 or greater, exceeding effect sizes reported for several psychological and medical diagnostic procedures.

Prevalence of malingering in patients with chronic pain referred for psychologic evaluation in a medico-legal context

OBJECTIVE

To provide an empirical estimate of the prevalence of malingered disability in patients with chronic pain who have financial incentive to appear disabled.

DESIGN

Retrospective review of cases.

SETTING

A private neuropsychologic clinic in a southeastern metropolitan area.

PARTICIPANTS

Consecutive patients (N=508) referred for psychologic evaluation related to chronic pain over a 10-year period (1995-2005).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Prevalence of malingering was examined using 2 published clinical diagnostic systems (Malingered Pain-Related Disability and Malingered Neurocognitive Dysfunction) as well as statistical estimates based on well validated indicators of malingering.

RESULTS

The prevalence of malingering in patients with chronic pain with financial incentive is between 20% and 50% depending on the diagnostic system used and the statistical model's underlying assumptions. Some factors associated with the medico-legal context such as the jurisdiction of a workers' compensation claim or attorney representation were associated with slightly higher malingering rates.

CONCLUSIONS

Malingering is present in a sizable minority of patients with pain seen for potentially compensable injuries. However, not all excess pain-related disability is a result of malingering. It is important not to diagnose malingering reflexively on the basis of limited or unreliable findings. A diagnosis of malingering should be explicitly based on a formal diagnostic system.

Sensitivity to brain dysfunction of the Halstead-Reitan vs an ability-focused neuropsychological battery

We compared the sensitivity to brain dysfunction of an ability focused neuropsychological battery (AFB), as a proxy for the core of a flexible battery, to the Halstead-Reitan Battery (HRB). The AFB was designed to represent constructs of language function, fine motor skill, working memory, processing speed, verbal and visual memory, and verbal and visual abstraction and problem solving. Receiver operating characteristic analysis (ROC) yielded an area under curve (AUC) of. 86 for the AFB, versus. 83 for the HRB (p =. 50), for discriminating 54 patients with brain dysfunction due to various etiologies, from 69 non-neurologic medical controls. Additionally, Bayesian Model Averaging selected four tests from the combined set of AFB and HRB subtests, plus Trail Making B, which optimally discriminated the brain dysfunction from medical control patients: H-Words, Grooved Pegboard, Finger Tapping, and Trail Making B. These data support the current mainstream practice in neuropsychology of using an AFB (flexible battery) to assess brain dysfunction. In particular, tests involving processing speed appear to be among the most sensitive measures of brain dysfunction. The data do not support the superiority of the HRB to AFB approaches.

Validity Testing in Dually Diagnosed Post-Traumatic Stress Disorder and Mild Closed Head Injury

Prospects for the coexistence of post-traumatic stress syndrome (PTSS) and mild traumatic brain injury (mTBI) rely exclusively on subjective evidence, increasing the risk of response bias in a compensatable social context. Using a priori specificities derived from genuine brain disorder groups, we examined validity failure rates in three domains (symptom, cognitive, motor) in 799 persons reporting persistent subjective disability long after mild neurological injury. Validity tests included the Test of Memory Malingering, MMPI-2 Fake Bad Scale, and Infrequency (F) scales, reliable digit span, and Halstead-Reitan finger tapping. Analyses showed invalidity signs in large excess of actuarial expectations, with rising invalidity risk conditional on post-traumatic complexity; the highest failure rates were produced by the 95 persons reporting both neurogenic amnesia and re-experiencing symptoms. We propose an "over-endorsement continuum" hypothesis: The more complex the post-traumatic presentation after mild neurological injury, the stronger the association with response bias. Late-appearing dual diagnosis is a litigation phenomenon so intertwined with secondary gain as to be a byproduct of it.

Neuropsychological correlates of manganese exposure: A meta-analysis

The hypothesized effect of recurrent low-dose manganese (Mn) exposure on neuropsychological function is controversial because of inconsistent findings across three decades of research. We conducted a meta-analysis on 41 variables from nineteen neuropsychological studies of Mn-exposed workers. The results showed: Large effect size (ES) for biological markers of Mn and lead levels; thirteen of 26 neurocognitive measures showing a small average ES; only one of 26 tasks showed a moderate ES; and small to medium ES for confounding/competing variables such as education and aptitude. Tasks with the highest ES included clerical substitution tasks, digit span, tapping endurance, and Swedish Performance Evaluation System "Additions" reaction time, but none exceeded the ES for education or aptitude. The mean ES of dose-response relationships was zero. The data did not support a theory of preclinical ("early") neuromotor or cognitive dysfunction. Overall, the pooled data are more consistent with covariate effect than toxic effect, insofar as the pooled exposure group showed demographics less favorable to neuropsychological performance than the pooled referent groups. Future consideration of demographic and biological covariates is necessary before inferring subtle toxin-induced brain damage because neuropsychological tests are nonspecific.

The prevalence of cognitive malingering in persons reporting exposure to occupational and environmental substances

OBJECTIVE

Directly estimate the prevalence of cognitive malingering in persons claiming exposure to occupational and environmental substances.

METHODS

Retrospective review of 128 neuropsychological cases with financial incentive. Estimates were based on two methods: (1) clinical identification using the Slick, Sherman and Iverson criteria for malingered neurocognitive dysfunction (MND), and (2) statistical modeling based on patient performance on several individual psychometric indicators of malingering.

RESULTS

The prevalence based on the clinical method was 40%. The statistically based estimates ranged from 30% to more than 45% depending on model parameters. Different incentive parameters may influence prevalence.

CONCLUSIONS

Cognitive malingering in toxic exposure is common and must be adequately addressed in the clinical neuropsychological assessment of toxic exposure and in research on its neurocognitive effects or findings will likely over-estimate the degree of cognitive impairment and related disability.

Detecting Insufficient Effort Using the Seashore Rhythm and Speech-Sounds Perception Tests in Head Injury

This study examined the capacity of the Seashore Rhythm Test (SRT) and the Speech-Sounds Perception Test (SSPT) to detect insufficient effort in a clinical sample. Forty-six participants with financially compensable mild head injury who obtained scores indicative of insufficient effort on multiple measures were compared to 49 participants with brain injury who were not involved in litigation. Receiver operating characteristic (ROC) curve analysis indicated that both the SRT (AUC = .84) and SSPT (AUC = .80) were significant (p < .001) predictors of insufficient effort. Maximizing sensitivity and specificity, the optimal cutoff scores were 8 errors on the SRT and 10 errors on the SSPT. Combining both variables into a logistic regression function increased the diagnostic efficiency.

The Fake Bad Scale and MMPI-2 F-family in detection of implausible psychological trauma claims

We tested the validity of the Lees-Haley Fake Bad Scale (FBS) and the family of MMPI-2 F scales (F-family; F, F(p), and F-K scales) in predicting improbable psychological trauma claims in an applied setting. Litigants reporting implausible symptoms long after minor scares and nonlitigants clinically referred following severe stressors completed the MMPI-2. Both groups were naturally matched on social class. The FBS demonstrated sensitivity, specificity, and positive predictive power in the detection of atypical problems but the F-family showed poor utility. FBS cutting scores derived from logistic regression were applied to a third group made up of litigants with histories of undeniably severe traumas. A substantial number of this third group scored above cutoffs for exaggeration, but this finding is ambiguous. Reasons for the F-family's insensitivity to real-world exaggeration may include using student simulators for validation and content reflective of psychotic simulation. The superiority of the FBS in applied forensic settings could derive from its development in actual litigants and content reflective of nonpsychotic exaggerations. The FBS appears acceptable for use in applied forensic settings where persons seek compensation for nonpsychotic syndromes.

SENSITIVITY AND SPECIFICITY OF FINGER TAPPING TEST SCORES FOR THE DETECTION OF SUSPECT EFFORT

Past studies indicate that patients with incentive to fake neuropsychological symptoms are likely to have lower finger tapping scores than credible patients. The present study builds upon past research by investigating finger tapping performance for seven groups: (a) noncredible patients (as determined by failed psychometric and behavioral criteria), and patients with (b) closed head injury, (c) dementia, (d) mental retardation, (e) psychosis, or (f) depression, and (g) healthy older controls. Results showed that men tapped faster than women, requiring that groups be divided by gender. Noncredible male and female patients tapped slower than their comparison group counterparts. Dominant hand score proved to be more sensitive to noncredible performance than other scores (nondominant, sum of both hands, difference between dominant and nondominant), especially for women. Sensitivity, specificity, and positive and negative predictive value tables are presented. With specificity set at 90% for the comparison groups combined, a dominant hand cutoff score of </=35 for men yielded 50% sensitivity, while a score of </=28 yielded 61% sensitivity for women. Specificity values for specific cutoff scores varied significantly across the comparison groups, indicating that cutoffs should be adjusted for the particular differential diagnosis. In conclusion, results indicate that when using finger tapping scores to detect noncredible performance: (a) Dominant hand performance is more sensitive, and (b) cutoffs should be selected based on gender and claimed diagnosis.

PROBABLE MALINGERING AND PERFORMANCE ON THE TEST OF VARIABLES OF ATTENTION

Fifty subjects with mild head injury involved in personal injury litigation and 2 subjects referred for evaluation of their disability status underwent comprehensive neuropsychological examination including the Test of Variables of Attention (TOVA). Group status was determined by performance on symptom validity testing. Twenty-six subjects who failed symptom validity testing formed the probable malingering (PM) group, while 26 subjects who passed symptom validity testing comprised the not malingering (NM) group. Subjects in the PM group performed significantly worse on all TOVA variables relative to subjects in the NM group. Discriminant function analyses revealed that TOVA omission errors >/=3 errors was the best predictor of group status. Malingering research employing a group of probable clinical malingerers has direct generalizability to real-world settings.

Methodological Problems in the Neuropsychological Assessment of Effects of Exposure to Welding Fumes and Manganese

Recently, Kaiser (2003) raised concerns over the increase in brain damage claims reportedly due to exposure to welding fumes. In the present article, we discuss methodological problems in conducting neuropsychological research on the effects of welding exposure, using a recent paper by Bowler et al. (2003) as an example to illustrate problems common in the neurotoxicity literature. Our analysis highlights difficulties in conducting such quasi-experimental investigations, including subject selection bias, litigation effects on symptom report and neuropsychological test performance, response bias, and scientifically inadequate casual reasoning.

The fake bad scale in atypical and severe closed head injury litigants

The correlational and diagnostic properties of Lees-Haley's MMPI-2 Fake Bad Scale (FBS) were examined in litigating atypical minor, litigating moderate-severe, and non-litigating moderate-severe head injury samples. Overall, the FBS was sensitive to both litigation status and nonconforming versus conforming symptom courses. The FBS appeared superior to the MMPI-2 F and F-K scales in differentiating atypical from real brain-injury outcomes. High FBS scorers also had higher scores on somatic complaining (Hs, Hy) and to a lesser degree with psychotic complaints (F, Pa, Sc). FBS showed significant associations with various neuropsychological symptom validity measures. FBS appears to capture a hybrid of infrequent symptom reporting styles with an emphasis on unauthentic physical complaints. However, FBS also correlated with documented abnormal neurological signs within a litigating moderate-severe brain-injury group. Its use as a symptom infrequency measure may have to be modified in more severe injury litigants, as some FBS items may reflect true long-term outcome in severe cerebral dysfunction.

Actual versus self-reported scholastic achievement of litigating postconcussion and severe closed head injury claimants

Psychologists typically rely on patients' self-report of premorbid status in litigated settings. The authors examined the fidelity between self-reported and actual scholastic performance in litigating head injury claimants. The data indicated late postconcussion syndrome (LPCS) and severe closed head injury litigants retrospectively inflated scholastic performance to a greater degree than nonlitigating control groups. The LPCS group showed the highest magnitude of grade inflation, but discrepancy scores did not significantly correlate with a battery of malingering measures or with objective cerebral dysfunction. These findings support previous studies, which showed self-report is not a reliable basis for estimation of preinjury cognitive status. Retrospective inflation may represent a response shift bias shaped by an adversarial context rather than a form of malingering.

Detecting exaggeration and malingering in neuropsychological assessment

Magnification of symptoms or nonoptimal effort on neuropsychological tests, within the context of head injury litigation, can have several independent or related underlying causes. Therefore, detecting exaggeration does not automatically indicate that the individual is malingering. This article reviews the evaluative and differential diagnostic process and provides the clinician with suggestions regarding assessment methods. A forensic evaluation that does not include careful consideration of possible negative response bias should be considered incomplete.

Is postural control associated with mental functioning in the persistent postconcussion syndrome?

OBJECTIVE

To investigate whether balance is associated with mental functioning after mild traumatic brain injury (MTBI).

DESIGN

Experimental two-group design.

SETTING

Outpatient rehabilitation department.

PATIENTS AND OTHER PARTICIPANTS

From a consecutive sample of referred MTBI patients, 15 subjects who complained of imbalance were included (8 men and 7 women, age 35.9+/-8.6yrs). Subjects with detectable neurologic impairments were excluded. Twenty healthy control subjects of the same age group also were tested.

MAIN OUTCOME MEASURES

In both groups, a force platform recorded center-of-pressure (CP) fluctuations during standing and weight shifting in different conditions. For the patients, attention and mental speed were assessed with the Symbol-Digit Substitution Test of the Wechsler Adult Intelligence Scale (Dutch version), verbal learning and memory were assessed with the 15-Words Test, and emotional distress was assessed with the Symptom Checklist-90.

RESULTS

Compared with controls, patients showed an overall increase of 60% in CP velocity and an overall weight-shifting speed 25% slower (p < .005), indicating static and dynamic postural instability. Only performance on the Symbol-Digit Substitution Test was associated with both static and dynamic balance (p < .02), giving an explained variance of over 40%.

CONCLUSION

The results indicate a possible association of balance with cognitive performance but not with emotional well-being after MTBI, suggesting an organic rather than a functional cause of postural instability. Further research is needed to assess the possible clinical implications.