Detecting malingered neurocognitive dysfunction using the reliable digit span in traumatic brain injury

Preliminary evidence for digit span performance validity indicators within the neuropsychological assessment battery

The purpose of this study was to evaluate multiple embedded performance validity indicators within the Digits Forward and Digits Backward subtests of the Neuropsychological Assessment Battery (NAB), including Reliable Digit Span (RDS), as no published papers have examined embedded digit span validity indicators within these subtests of the NAB. Retrospective archival chart review was conducted at an outpatient neuropsychology clinic. Participants were 92 adults (ages 19-68) who completed NAB Digits Forward and Digits Backward, and the Word Choice Test (WCT). Receiver operating characteristic (ROC) curves, t-tests, and sensitivity and specificity analyses were conducted. Analyses showed that RDS demonstrated acceptable classification accuracy between those who passed the WCT and those who did not. The area under the curve (AUC) value for RDS was 0.702; however, AUC values for all other digit span indices were unacceptably low. The optimal cutoff for RDS was identified (<8). RDS for the NAB appears to be an adequate indicator of performance validity; however, considering the very small number of participants who were invalid on the WCT (n = 15), as well as the utilization of only one stand-alone PVT to classify validity status, these findings are preliminary and in need of replication.

The classification accuracy of Warrington's recognition memory test (words) as a performance validity Test in a neurorehabilitation setting

This study was designed to evaluate the classification accuracy of the Warrington's Recognition Memory Test (RMT) in 167 patients (97 or 58.1% men; MAge = 40.4; MEducation= 13.8) medically referred for neuropsychological evaluation against five psychometrically defined criterion groups. At the optimal cutoff (≤42), the RMT produced an acceptable combination of sensitivity (.36-.60) and specificity (.85-.95), correctly classifying 68.4-83.3% of the sample. Making the cutoff more conservative (≤41) improved specificity (.88-.95) at the expense of sensitivity (.30-.60). Lowering the cutoff to ≤40 achieved uniformly high specificity (.91-.95) but diminished sensitivity (.27-.48). RMT scores were unrelated to lateral dominance, education, or gender. The RMT was sensitive to a three-way classification of performance validity (Pass/Borderline/Fail), further demonstrating its discriminant power. Despite a notable decline in research studies focused on its classification accuracy within the last decade, the RMT remains an effective free-standing PVT that is robust to demographic variables. Relatively low sensitivity is its main liability. Further research is needed on its cross-cultural validity (sensitivity to limited English proficiency).

Wisconsin Card Sorting Task-64 performance among HIV+ Black/African American and Latinx adults compared to normative samples and by sociocultural and health variables

Many people living with HIV experience cognitive impairment, and HIV disproportionately affects racial/ethnic minority groups. Independent of HIV, racial/ethnic minority individuals perform worse than White individuals on cognitive tasks, even after accounting for education. Our goals were to (1) compare WCST-64 scores between HIV+ Black/African American (Black/AA) (n = 45) and Latinx (n = 41) urban-dwelling adults; (2) compare our total sample to the WCST-64 manual's normative (N) and clinical normative (CN) groups; and (3) explore relationships between WCST-64 performance and sociocultural/health variables. In our sample, employment (12%), mean annual income (<$10,000), and mean education (<12 years) were low, while mean medication adherence rates were high for both Black/AA (90%) and Latinx (87%). WCST-64 scores were similar between groups (p > .05). Percentages of "below average" and "mildly impaired" scores in our sample were higher than the N group, and similar to the CN group. Lifetime heroin use, dementia, and longer HIV illness duration were significantly associated with worse WCST-64 performance (ps < .05). The observed low scores in our asymptomatic sample are likely due to the intersectionality of sociocultural and medical burden, highlighting complexities in interpreting neuropsychological data in real-world HIV+ clinics. Executive deficits are linked to poorer outcomes, and routine cognitive screening may be clinically indicated.

Considerations for Reliable Digit Span as a performance validity test for long-term survivors of childhood brain tumors

The Reliable Digit Span (RDS) is a performance validity test (PVT) used widely within non-clinical samples, but its utility is in question in clinical groups with cognitive impairment. To investigate, RDS scores were calculated and correlated with the Neurological Predictor Scale, an informant-reported Activities of Daily Living score, and a proxy measure of intelligence (Vocabulary) for 83 adult survivors of childhood brain tumors and 105 healthy controls. Analyses were covaried for age at examination. Participants were divided into passing and failing groups at each RDS cutoff, and ANCOVAs for each of the three variables of interest covaried for age at the examination were run. RDS was correlated with all three variables of interest in survivors but only Vocabulary in controls. At the ≤7 cutoff, passing and failing survivors demonstrated significant differences across all variables of interest, while passing and failing controls differed only on Vocabulary. Differences were also found between passing and failing survivors at lower cutoffs. RDS is related to and likely impacted by various neurological and cognitive challenges faced by brain tumor survivors. Using the standard RDS cutoff of ≤7 may result in inaccurate interpretation of valid performance in this population; therefore, the use of other PVTs is recommended.

Multivariate Models of Performance Validity: The Erdodi Index Captures the Dual Nature of Non-Credible Responding (Continuous and Categorical)

This study was designed to examine the classification accuracy of the Erdodi Index (EI-5), a novel method for aggregating validity indicators that takes into account both the number and extent of performance validity test (PVT) failures. Archival data were collected from a mixed clinical/forensic sample of 452 adults referred for neuropsychological assessment. The classification accuracy of the EI-5 was evaluated against established free-standing PVTs. The EI-5 achieved a good combination of sensitivity (.65) and specificity (.97), correctly classifying 92% of the sample. Its classification accuracy was comparable with that of another free-standing PVT. An indeterminate range between Pass and Fail emerged as a legitimate third outcome of performance validity assessment, indicating that the underlying construct is an inherently continuous variable. Results support the use of the EI model as a practical and psychometrically sound method of aggregating multiple embedded PVTs into a single-number summary of performance validity. Combining free-standing PVTs with the EI-5 resulted in a better separation between credible and non-credible profiles, demonstrating incremental validity. Findings are consistent with recent endorsements of a three-way outcome for PVTs (Pass, Borderline, and Fail).

Path Analysis of the Mediating Roles of Personality, Distress, and Cognitive Flexibility in the Subjective Well-Being of Combat Veterans With Traumatic Brain Injury

OBJECTIVE

To determine the interrelationships among traumatic brain injury (TBI), maladaptive personality traits (MPT), psychological distress, and cognitive flexibility in the prediction of subjective well-being of post-9/11 veterans concurrently and over time.

SETTING

Five Veterans Affairs (VA) medical centers and 1 VA outpatient clinic in urban, suburban, and rural areas.

PARTICIPANTS

Five hundred Operation Enduring Freedom/Operation Iraqi Freedom veterans at baseline (219 with TBI), 292 at 18-month follow-up (108 with TBI), drawn from a regional registry and clinic referrals.

DESIGN

Path analysis of data from a prospective cohort study.

MAIN MEASURES

Satisfaction with Life Scale, 36-ltem Short-Form Health Survey (SF-36) Health Scale, Personality Assessment Screener, Beck Depression Inventory-II, Beck Anxiety Inventory, Posttraumatic Stress Disorder Checklist-Military, Trail Making Test, Part B, Delis-Kaplan Executive Function System (D-KEFS) Category-Switching Verbal Fluency, and D-KEFS Color-Word Interference Test.

RESULTS

There was no direct effect of TBI on well-being at baseline or 18 months later. Psychological distress, MPT, and cognitive flexibility had significant direct effects on well-being at baseline and 18 months. Baseline model accounted for 66% of the variance in well-being; follow-up model accounted for 43% of well-being variance. Negative influence of distress significantly decreased from baseline to follow-up. Direct negative effect of MPT diminished slightly over 18 months; effect of cognitive flexibility increased. Significant relationships were estimated in prediction of distress by MPT, cognitive flexibility, and TBI. TBI predicted MPT. MPT, cognitive flexibility, and TBI had indirect effects on well-being. TBI had a positive indirect influence on distress. Total effects included 4 significant predictors of well-being at baseline and 18 months: distress, MPT, cognitive flexibility, and TBI.

CONCLUSION

Experience of TBI alone did not predict subjective well-being at baseline or 18 months later. Psychological distress, MPT, and cognitive flexibility had direct effects on well-being at both time points. Interventions aimed at reducing distress and bolstering resilience and cognitive flexibility are recommended to increase subjective well-being in this population.

Critical Item Analysis Enhances the Classification Accuracy of the Logical Memory Recognition Trial as a Performance Validity Indicator

OBJECTIVE

: Replicate previous research on Logical Memory Recognition (LM_Recog) and perform a critical item analysis.

METHOD

: Performance validity was psychometrically operationalized in a mixed clinical sample of 213 adults. Classification of the LM_Recog and nine critical items (CR-9) was computed.

RESULTS

: LM_Recog ≤20 produced a good combination of sensitivity (.30-.35) and specificity (.89-.90). CR-9 ≥5 and ≥6 had comparable classification accuracy. CR-9 ≥5 increased sensitivity by 4% over LM_Recog ≤20; CR-9 ≥6 increased specificity by 6-8% over LM_Recog ≤20; CR-9 ≥7 increased specificity by 8-15%.

CONCLUSIONS

: Critical item analysis enhances the classification accuracy of the optimal LM_Recog cutoff (≤20).

Five shades of gray: Conceptual and methodological issues around multivariate models of performance validity

OBJECTIVE

This study was designed to empirically investigate the signal detection profile of various multivariate models of performance validity tests (MV-PVTs) and explore several contested assumptions underlying validity assessment in general and MV-PVTs specifically.

METHOD

Archival data were collected from 167 patients (52.4%male; MAge = 39.7) clinicially evaluated subsequent to a TBI. Performance validity was psychometrically defined using two free-standing PVTs and five composite measures, each based on five embedded PVTs.

RESULTS

MV-PVTs had superior classification accuracy compared to univariate cutoffs. The similarity between predictor and criterion PVTs influenced signal detection profiles. False positive rates (FPR) in MV-PVTs can be effectively controlled using more stringent multivariate cutoffs. In addition to Pass and Fail, Borderline is a legitimate third outcome of performance validity assessment. Failing memory-based PVTs was associated with elevated self-reported psychiatric symptoms.

CONCLUSIONS

Concerns about elevated FPR in MV-PVTs are unsubstantiated. In fact, MV-PVTs are psychometrically superior to individual components. Instrumentation artifacts are endemic to PVTs, and represent both a threat and an opportunity during the interpretation of a given neurocognitive profile. There is no such thing as too much information in performance validity assessment. Psychometric issues should be evaluated based on empirical, not theoretical models. As the number/severity of embedded PVT failures accumulates, assessors must consider the possibility of non-credible presentation and its clinical implications to neurorehabilitation.

Applying the British picture vocabulary scale to estimate premorbid cognitive ability in adults

Estimating premorbid cognitive ability is an essential part of assessment as well as being an important consideration in research. The most widely used approach to premorbid assessment, The National Adult Reading Test (NART), relies on word reading ability. However, this can be problematic in patients where communication is impaired. This research assessed the effectiveness of a receptive vocabulary test, the British Picture Vocabulary Scale II (BPVS) as an alternative. Correlations were found between the BPVS, NART and the Weschler Abbreviated Scale of Intelligence (WASI) in 87 healthy participants. Regression equations were calculated relating NART and BPVS raw scores to IQ scores in the healthy sample. WASI, NART and BPVS scores were also obtained in 19 patients with varying neurological etiology as part of their routine assessment. Results showed that 18 out of 19 patients obtained BPVS derived IQ scores similar to or higher than their WASI IQ. Whereas mean BPVS derived IQ did not differ significantly between the standardization and clinical samples, WASI IQ scores were lower in the patient group. The findings suggest that the BPVS II 'holds' after acquired cognitive impairment and is a promising alternative method for estimating premorbid IQ in patients who have difficulties reading or verbalizing.

Cultural accommodations for cutoff scores of embedded performance validity tests in a Spanish college population

OBJECTIVE

The objective of this study was to identify specific cutoff scores for three commonly used embedded performance validity tests (PVTs) for a Spanish speaking population. Culturally adapted cutoff scores for embedded PVTs were established using an analog study design. In addition, the psychometric properties of these measures when applying culturally adapted scores as compared to non-adapted scores were analyzed.

METHOD

Participants (N = 114) were administered three embedded PVTs (Reliable Digit Span, Phonetic Fluency Test, and Animal Semantic Fluency Test) in a randomized order. Following an analog design, control participants were instructed to perform to the best of their abilities and the analog group was instructed to simulate cognitive impairment.

RESULTS

In keeping with guidelines for specificity and sensitivity, the most culturally appropriate scores of ≤6, ≤27, and ≤16 were determined for the Reliable Digit Span, Phonetic Fluency Test, and the Semantic Fluency Test, respectively.

CONCLUSIONS

This the first study addressing culturally sensitive cutoffs for commonly used embedded validity measures using a European Spanish population. While these findings cannot be generalized to forensic or clinical populations at the present time, they support the claim that specific cutoff scores that are sensitive to cultural variables are necessary in addressing embedded validity measures of the Reliable Digit Span, Phonetic Fluency Test, and Semantic Fluency Test.

Stronger Together: The Wechsler Adult Intelligence Scale-Fourth Edition as a Multivariate Performance Validity Test in Patients with Traumatic Brain Injury

OBJECTIVE

This study was designed to evaluate the classification accuracy of a multivariate model of performance validity assessment using embedded validity indicators (EVIs) within the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV).

METHOD

Archival data were collected from 100 adults with traumatic brain injury (TBI) consecutively referred for neuropsychological assessment in a clinical setting. The classification accuracy of previously published individual EVIs nested within the WAIS-IV and a composite measure based on six independent EVIs were evaluated against psychometrically defined non-credible performance.

RESULTS

Univariate validity cutoffs based on age-corrected scaled scores on Coding, Symbol Search, Digit Span, Letter-Number-Sequencing, Vocabulary minus Digit Span, and Coding minus Symbol Search were strong predictors of psychometrically defined non-credible responding. Failing ≥3 of these six EVIs at the liberal cutoff improved specificity (.91-.95) over univariate cutoffs (.78-.93). Conversely, failing ≥2 EVIs at the more conservative cutoff increased and stabilized sensitivity (.43-.67) compared to univariate cutoffs (.11-.63) while maintaining consistently high specificity (.93-.95).

CONCLUSIONS

In addition to being a widely used test of cognitive functioning, the WAIS-IV can also function as a measure of performance validity. Consistent with previous research, combining information from multiple EVIs enhanced the classification accuracy of individual cutoffs and provided more stable parameter estimates. If the current findings are replicated in larger, diagnostically and demographically heterogeneous samples, the WAIS-IV has the potential to become a powerful multivariate model of performance validity assessment.

BRIEF SUMMARY

Using a combination of multiple performance validity indicators embedded within the subtests of theWechsler Adult Intelligence Scale, the credibility of the response set can be establishedwith a high level of confidence. Multivariatemodels improve classification accuracy over individual tests. Relying on existing test data is a cost-effective approach to performance validity assessment.

I think, therefore I forget - using experimental simulation of dementia to understand functional cognitive disorders

BACKGROUND

Symptoms of functional neurological disorder have traditionally been thought to depend, in part, on patients' ideas about symptoms rather than on the rules of pathophysiology. The possibility that functional cognitive symptoms might similarly reflect ideas of dementia has not been explored. We aimed to assess beliefs, through performance, about symptoms of dementia in healthy non-medical adults with the intention of identifying potential markers of functional cognitive disorders.

METHODS

Healthy volunteers were asked to simulate symptoms of mild dementia during testing with the Montreal Cognitive Assessment (MoCA), coin-in-hand forced-choice test, short digit span trials, Luria 3-step test and interlocking finger test. Family history of dementia was recorded.

RESULTS

In 50 participants aged 18-27, simulating dementia, mean MoCA score was 16 (SD 5.5, range 5-26). Delayed recall was the most frequently failed item (100%) and cube drawing least frequently failed (42%). Twenty-six percent failed forward three-digit span and 36% failed reverse two-digit span. On the coin-in-hand test, 32% scored at or below chance level. Inconsistent response patterns were common.

CONCLUSIONS

Cognitively healthy young adults simulating mild dementia perform similarly to older adults with mild dementia, demonstrating beliefs that dementia is associated with significant global impairment, including attention, motor function, and letter vigilance, but preservation of cube drawing. Inconsistent response patterns were common. Contrary to expectation, family history of dementia did not influence performance. Two and three digit span showed particular promise as a bedside test for simulation. Further investigation will establish whether similar patterns of results are produced in individuals with functional cognitive symptoms.

Prefrontal gray matter volume predicts metacognitive accuracy following traumatic brain injury

OBJECTIVE

To examine metacognitive ability (MC) following moderate to severe traumatic brain injury (TBI) using an empirical assessment approach and to determine the relationship between alterations in gray matter volume (GMV) and MC.

METHOD

A sample of 62 individuals (TBI n = 34; healthy control [HC] n = 28) were included in the study. Neuroimaging and neuropsychological data were collected for all participants during the same visit. MC was quantified using an approach borrowed from signal detection theory (Type II area under the receiver operating characteristic curve calculation) to evaluate judgments during a modified version of the 3rd edition of the Wechsler Adult Intelligence Scale's Matrix Reasoning subtest where half of the items were presented randomly and half were presented in the order of increasing difficulty. Retrospective confidence judgments were collected on an item-by-item basis. Brain volumetric analyses were conducted using FreeSurfer software.

RESULTS

Analyses of the modified Matrix Reasoning task data demonstrated that HCs significantly outperformed TBIs (ordered: d = .63; random: d = .58). There was a significant difference between groups for MC for the randomly presented stimuli (d = .54) but not the ordered stimuli. There was an association between GMV and MC in the TBI group between the right orbital region and MC (R2 = .11). In the HC group, there were associations between the left posterior (R2 = .17), left orbital (R2 = .29), and left dorsolateral (R2 = .21) regions and MC.

CONCLUSIONS

These results are consistent with those of previous research on MC in the cognitive neurosciences, but this study demonstrates that injury may moderate the regional contributions to MC. (PsycINFO Database Record

Preliminary Validation of the Rey 15-Item Test and Reliable Digit Span in Native Japanese Samples

The Rey 15-Item Test and reliable digit span were evaluated in Japan. Participants were controls ( n = 15), healthy volunteers instructed to simulate memory impairment ( n = 12; 5 of 17 volunteers did not comply with instructions and were dropped), healthy elderly ( n = 12), and cognitively disabled nursing home residents ( n = 8). On the 15-Item Test, controls and elderly performed similarly and were combined. Nursing home residents could not cope with the 15-Item Test and were dropped. Total score was a fair predictor of dissimulation using a cutoff ≤ 8. Rows were fair predictors using a ≤2 cutoff. Sensitivities were low and specificities were excellent. Reliable digit span contrasts between simulators and each of the other groups demonstrated that reliable digit span discriminated controls and elderly from simulators (≤6 and ≤5 cutoffs). Sensitivities were moderate and specificities were excellent. Reliable digit span did not differentiate simulators from nursing home residents.

Reliable Digit Span: Does it Adequately Measure Suboptimal Effort in an Adult Epilepsy Population?

Objective

Assessment of performance validity is a necessary component of any neuropsychological evaluation. Prior research has shown that cutoff scores of ≤6 or ≤7 on Reliable Digit Span (RDS) can detect suboptimal effort across numerous adult clinical populations; however, these scores have not been validated for that purpose in an adult epilepsy population. This investigation aims to determine whether these previously established RDS cutoff scores could detect suboptimal effort in adults with epilepsy.

Method

Sixty-three clinically referred adults with a diagnosis of epilepsy or suspected seizures were administered the Digit Span subtest of the Wechsler Adult Intelligence Scale (WAIS-III or WAIS-IV). Most participants (98%) passed Trial 2 of the Test of Memory Malingering (TOMM), achieving a score of ≥45.

Results

Previously established cutoff scores of ≤6 and ≤7 on RDS yielded a specificity rate of 85% and 77% respectively. Findings also revealed that RDS scores were positively related to attention and intellectual functioning. Given the less than ideal specificity rate associated with each of these cutoff scores, together with their strong association to cognitive factors, secondary analyses were conducted to identify more optimal cutoff scores. Preliminary results suggest that an RDS cutoff score of ≤4 may be more appropriate in a clinically referred adult epilepsy population with a low average IQ or lower.

Conclusions

Preliminary findings indicate that cutoff scores of ≤6 and ≤7 on RDS are not appropriate in adults with epilepsy, especially in individuals with low average IQ or below.

Concordance validity of PVTs in a sample of veterans referred for mild TBI

Concordance validity of commonly used performance validity tests (PVTs) was assessed in a sample of Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn (OEF/OIF/OND) veterans referred to an mTBI screening clinic in a south-eastern Veterans Affairs hospital. Veteran service members (total n = 184) completed the Rey-15, Repeatable Battery of the Assessment for Neuropsychological Status Effort Index (RBANS EI), and Reliable Digit Span (RDS) from the Wechsler Intelligence Scales. Kappa coefficients and percentage of agreement were established to determine the level of concordance between the three measures. PVT failure rate ranged from 7.4% of the sample (Rey-15) to 26.1% (RBANS EI Liberal). The highest concordance was found between the Rey 15 and RBANS EI "highly suspicious" cut-off, with the lowest agreement noted between all PVTs and the RBANS EI "liberal" cut-score. All concordance coefficients fell within the fair to moderate levels. Overall, the observed agreement between the explored measures was generally consistent with or greater than other studies of PVT concordance. Given the rates of concordance, the current results continue to suggest that PVTs are likely to measure a construct separate from the typical cognitive domains.

Aggregating validity indicators: The salience of domain specificity and the indeterminate range in multivariate models of performance validity assessment

This study was designed to examine the "domain specificity" hypothesis in performance validity tests (PVTs) and the epistemological status of an "indeterminate range" when evaluating the credibility of a neuropsychological profile using a multivariate model of performance validity assessment. While previous research suggests that aggregating PVTs produces superior classification accuracy compared to individual instruments, the effect of the congruence between the criterion and predictor variable on signal detection and the issue of classifying borderline cases remain understudied. Data from a mixed clinical sample of 234 adults referred for cognitive evaluation (M_Age = 46.6; M_Education = 13.5) were collected. Two validity composites were created: one based on five verbal PVTs (EI-5_VER) and one based on five nonverbal PVTs (EI-5_NV) and compared against several other PVTs. Overall, language-based tests of cognitive ability were more sensitive to elevations on the EI-5_VER compared to visual-perceptual tests; whereas, the opposite was observed with the EI-5_NV. However, the match between predictor and criterion variable had a more complex relationship with classification accuracy, suggesting the confluence of multiple factors (sensory modality, cognitive domain, testing paradigm). An "indeterminate range" of performance validity emerged that was distinctly different from both the Pass and the Fail group. Trichotomized criterion PVTs (Pass-Borderline-Fail) had a negative linear relationship with performance on tests of cognitive ability, providing further support for an "in-between" category separating the unequivocal Pass and unequivocal Fail classification range. The choice of criterion variable can influence classification accuracy in PVT research. Establishing a Borderline range between Pass and Fail more accurately reflected the distribution of scores on multiple PVTs. The traditional binary classification system imposes an artificial dichotomy on PVTs that was not fully supported by the data. Accepting "indeterminate" as a legitimate third outcome of performance validity assessment has the potential to improve the clinical utility of PVTs and defuse debates regarding "near-Passes" and "soft Fails."

Hyperarousal Symptoms Explain the Relationship Between Cognitive Complaints and Working Memory Performance in Veterans Seeking PTSD Treatment

OBJECTIVE

Comorbidity and symptom overlap between traumatic brain injury and posttraumatic stress disorder (PTSD) in veterans returning from deployment present challenges with respect to differential diagnosis and treatment. Both conditions frequently manifest with attention and working memory deficits, though the underlying neuropsychological basis differs. This study evaluated whether hyperarousal symptoms explain the relationship between subjective and objective measures of cognition in a veteran sample.

PARTICIPANTS AND PROCEDURES

One-hundred three veterans completed the military version of the PTSD Checklist (PCL), the Neurobehavioral Symptom Inventory, and the Wechsler Memory Scale, 3rd edition digit span task with adequate effort.

RESULTS

Hierarchical regression suggested that hyperarousal, but not other PTSD symptoms, explained the relationship between neurobehavioral symptoms and cognitive functioning. This relationship was present regardless of whether veterans met full PTSD diagnostic criteria or screened positive on a traumatic brain injury screener and was robust to other moderators.

CONCLUSION

These findings highlight the importance of considering traumatic brain injury and PTSD symptom overlap, particularly the relationship between hyperarousal symptoms and attention and working memory deficits, in conceptualizing cases and treatment planning.

WAIS Digit Span-Based Indicators of Malingered Neurocognitive Dysfunction

The present study determined specificity and sensitivity to malingered neurocognitive dysfunction (MND) in traumatic brain injury (TBI) for several Wechsler Adult Intelligence Scale (WAIS) Digit Span scores. TBI patients (n = 344) were categorized into one of five groups: no incentive, incentive only, suspect, probable MND, and definite MND. Performance of 1,063 nonincentive patients (e.g., cerebrovascular accident, memory disorder) was also examined. Digit Span scores included reliable digit span, maximum span forward both trials correct, maximum span forward, combined maximum forward and backward span, Digit Span scaled score, maximum span backward both trials correct, and maximum span backward. In TBI, sensitivity to MND ranged from 15% to greater than 30% at specificities of 92% to 98%. Patient groups with documented brain pathology had higher false-positive error rates. These results replicate previous known-groups malingering studies and provide valuable data supporting the WAIS Digit Span scores in detection and diagnosis of malingering.

California Verbal Learning Test Indicators of Malingered Neurocognitive Dysfunction

The present study used well-defined traumatic brain injury (TBI) and mixed neurological (other than TBI) and psychiatric samples to examine the specificity and sensitivity to Malingered Neurocognitive Dysfunction (MND) of four individual California Verbal Learning Test (CVLT) variables and eight composite CVLT malingering indicators. Participants were 275 traumatic brain injury and 352 general clinical patients seen for neuropsychological evaluation. The TBI patients were assigned to one of five groups using the Slick, Sherman, and Iverson (1999) criteria: no incentive, incentive only, suspect, and malingering (both Probable MNDand Definite MND). Within TBI, persons with the strongest evidence for malingering (Probable and Definite) had the most extreme scores. Good sensitivity (approximately 50%) in the context of excellent specificity (> 95%) was found in the TBI samples. Issues related to the appropriate clinical application of these data are discussed.

Reliable Digit Span is Unaffected by Laboratory-Induced Pain

Reliable Digit Span (RDS) is an indicator used to assess the validity of cognitive test performance. Scores of 7 or lower suggest poor effort or negative response bias. The possibility that RDS scores are also affected by pain has not been addressed thus potentially threatening RDS specificity. The current study used cold pressor-induced pain to investigate the effect of pain on RDS scores. Sixty undergraduate volunteers randomly assigned to one of three conditions (control, simulator, pain) completed the Digit Span subtest from the Wechsler Adult Intelligence Scale-III from which the RDS is derived. No differences in RDS scores were found between the control and pain groups, and neither group scored below 8. Sixty-five percent of the simulator group scored 7 or below. These results suggest that RDS is not affected by pain, and scores of 7 or less in persons with pain can be more confidently attributed to negative response bias.

Sensitivity and Specificity of Reliable Digit Span in Malingered Pain-Related Disability

The reliable digit span (RDS) performance of chronic pain patients with unambiguous spinal injuries and no evidence of exaggeration or response bias (n = 53) was compared to that of chronic pain patients meeting criteria for definite malingered neurocognitive dysfunction (n = 35), and a group of nonmalingering moderate-severe traumatic brain injury (TBI) patients (n = 69). The results demonstrated that scores of 7 or lower were associated with high specificity (> .90) and sensitivity (up to .60) even when moderate to severe TBI are included. Multiple studies have demonstrated that RDS scores of 7 or lower rarely occur in TBI and pain patients who are not intentionally performing poorly on cognitive testing. This study supports the use of the RDS in detecting response bias in neuropsychological patients complaining of pain as well as in the assessment of pain-related cognitive impairment in patients whose primary complaint is pain.

Malingering in Toxic Exposure

This study examined the sensitivity and false-positive error rate of reliable digit span (RDS) and the WAIS-III Digit Span (DS) scaled score in persons alleging toxic exposure and determined whether error rates differed from published rates in traumatic brain injury (TBI) and chronic pain (CP). Data were obtained from the files of 123 persons referred for neuropsychological evaluation related to alleged exposure to environmental and industrial substances. Malingering status was determined using the criteria of Slick, Sherman, and Iverson (1999). The sensitivity and specificity of RDS and DS in toxic exposure are consistent with those observed in TBI and CP. These findings support the use of these malingering indicators in cases of alleged toxic exposure and suggest that the classification accuracy data of indicators derived from studies of TBI patients may also be validly applied to cases of alleged toxic exposure.

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.

Derivation and Cross-Validation of Cutoff Scores for Patients With Schizophrenia Spectrum Disorders on WAIS-IV Digit Span–Based Performance Validity Measures

Two studies were conducted to identify and cross-validate cutoff scores on the Wechsler Adult Intelligence Scale–Fourth Edition Digit Span–based embedded performance validity (PV) measures for individuals with schizophrenia spectrum disorders. In Study 1, normative scores were identified on Digit Span–embedded PV measures among a sample of patients ( n = 84) with schizophrenia spectrum diagnoses who had no known incentive to perform poorly and who put forth valid effort on external PV tests. Previously identified cutoff scores resulted in unacceptable false positive rates and lower cutoff scores were adopted to maintain specificity levels ≥90%. In Study 2, the revised cutoff scores were cross-validated within a sample of schizophrenia spectrum patients ( n = 96) committed as incompetent to stand trial. Performance on Digit Span PV measures was significantly related to Full Scale IQ in both studies, indicating the need to consider the intellectual functioning of examinees with psychotic spectrum disorders when interpreting scores on Digit Span PV measures.

Effort in acute traumatic brain injury: considering more than pass/fail

PURPOSE/OBJECTIVE

Performance validity is often conceptualized as a dichotomous process. Effort likely lies on a continuum, however, and psychologists' tendency to rely on pass/fail descriptors of one's effort may not be the only approach. The current study aims to show that when performance validity is considered on a continuum, it may provide clinical information related to cognitive functioning.

RESEARCH METHOD/DESIGN

Forty-four patients with moderate or severe traumatic brain injury were evaluated with the Repeatable Battery for the Assessment of Neuropsychological Status upon their emergence from posttraumatic amnesia. From this data, previously developed effort index scores and "other cognitive functions" index scores were calculated.

RESULTS

Performance on the effort index significantly accounted for the patients' performance on a cognitive composite score after considering education and severity of injury.

CONCLUSIONS/IMPLICATIONS

Findings suggest that more in-depth analysis of validity test performance is beneficial to gauge a patient's level of effort and is important to consider when interpreting results and in treatment planning.

Unreliable block span reveals simulated intellectual disability on the stanford-binet intelligence scales-fifth edition

Previously developed validity measures are largely lacking in their ability to accurately distinguish malingerers from individuals with genuine intellectual disabilities (ID). The purpose of the present study was to develop a validity index for the Stanford-Binet Intelligence Scales-Fifth Edition (SB-5) aimed at detecting malingered ID. Fifty-four college students were instructed to feign impairment consistent with mental retardation while completing the SB-5. Simulated malingerers performed significantly poorer on the Block Span task of the SB-5 than did individuals with genuine impairment. A Block Span Validity Index (BSVI) cutoff score of less than 10 showed perfect specificity by correctly identifying all persons with true ID and demonstrated 52% sensitivity in identifying persons feigning impairment. For the detection of malingered ID, the BSVI yielded favorable results, although more research is needed to validate the BSVI using a known-groups study design.

Systemically treated breast cancer patients and controls: an evaluation of the presence of noncredible performance

This study sought to define the frequency of noncredible performance in breast cancer patients before, during and after completion of systemic treatment, as well as predictors of noncredible performance. We examined six datasets investigating the cognitive effects of chemotherapy and/or endocrine therapy. Embedded performance validity test (PVT) measures were identified and used to evaluate the datasets. One dataset included a standalone PVT. Possible noncredible performance was operationally defined as performance below criterion on three or more PVT indices. This was undertaken as cancer patients have been observed clinically to fail PVTs both in the context of external gain and independent of such motivators. A total of 534 breast cancer patients and 214 healthy controls were included in the analysis. Percentages of patients performing below cutoff on one or more PVT varied from 0% to 21.2%. Only 1 patient met the criterion of noncredible performance. Calculation of post-test probabilities indicated a more than 90% chance to detect noncredible performance. There is no evidence to suggest noncredible performance in breast cancer patients and healthy controls who choose to participate in research studies examining cognitive function. Thus, the observational data showing that non-central nervous system (CNS) cancer and therapies not targeting the CNS can have untoward effects on cognitive function are unlikely to be due to noncredible performance.

A normative study of the digit span in an educationally diverse elderly population

OBJECTIVE

The purpose of this study was to explore the effect of demographic variables on Digit Span test (DS) performance in an educationally diverse elderly population and to provide normative information.

METHODS

The DS was administered to 784 community-dwelling volunteers aged 60-90 years with an educational history of from zero to 25 years of full-time education. People with serious neurological, medical and psychiatric disorders (including dementia) were excluded.

RESULTS

Age, education and gender were found to be significantly associated with performance on the DS. Based on the results obtained, DS norms were stratified by age (2 strata), education (3 strata), and gender (2 strata).

CONCLUSION

Our results on DS performance suggest that both attention and working memory are influenced by age, education and gender. The present study provides reasonably comprehensive normative information on the DS for an educationally diverse elderly population.

Traumatic brain injury: guidance in a forensic context from outcome, dose-response, and response bias research

Traumatic brain injury (TBI) occurs at a high incidence, involving millions of individuals in the U.S. alone. Related to this, there are large numbers of litigants and claimants who are referred annually for forensic evaluation. In formulating opinions regarding claimed injuries, the present review advises experts to rely on two sets of information: TBI outcome and neuropsychological dose-response studies of non-litigants and non-claimants, and response bias literature that has demonstrated the relatively high risk of invalid responding among examinees referred within a secondary gain context, which in turn has resulted in the development of specific assessment methods. Regarding prospective methods for detecting possible response bias, both symptom validity tests, for measuring over-reporting of symptoms on inventories and questionnaires, and performance validity tests, for measuring insufficient effort on ability tests, are considered essential.