Differentiating epilepsy from psychogenic nonepileptic seizures using neuropsychological test data

Neuropsychological characteristics of drug resistant epilepsy patients with and without comorbid functional seizures

INTRODUCTION

Neuropsychological testing is a mandatory component in the evaluation of drug resistant epilepsy. The results of testing may assist with both the localization of an epilepsy as well as assessment of surgical risk. Previous studies have demonstrated differences in the neuropsychological performance of patients with epilepsy and functional seizures. We hypothesized that comorbid functional seizures could potentially influence neuropsychological test performance. Therefore, we evaluated whether there is a difference in the neuropsychological test results between drug resistant epilepsy patients with and without comorbid functional seizures.

METHOD

Neuropsychological test results were compared between 25 patients with drug resistant focal epilepsy and 25 patients that also had documented functional seizures. Univariate analyses and multiple logistic regression models were used to both assess performance differences between the groups and to assess whether test results could be used to accurately identify which patients had comorbid functional seizures.

RESULTS

Epilepsy patients with comorbid functional seizures performed significantly worse on the FAS Verbal Fluency Test compared to ES patients (p = 0.047). Digit Span Backwards (p = 0.10), Digit Span Forwards (p = 0.14) and Working Memory Index (p = 0.10) tended to be lower in the epilepsy and functional seizures group but was not statistically significant. A multiple logistic regression model using the results of four neuropsychological tests was able to identify patients with comorbid functional seizures with 83.33% accuracy.

CONCLUSIONS

There are appeared to be some differences in the neuropsychological performance among drug resistant epilepsy patients based on whether they have comorbid functional seizures. These findings may have relevant implications for the interpretation of neuropsychological test results.

Objective and subjective neurocognitive functioning in functional motor symptoms and functional seizures: preliminary findings

INTRODUCTION

This study aimed to provide a preliminary assessment of objective and subjective neurocognitive functioning in individuals with functional motor symptoms (FMS) and/or functional seizures (FS). We tested the hypotheses that the FMS/FS group would display poorer objective attentional and executive functioning, altered social cognition, and reduced metacognitive accuracy.

METHOD

Individuals with FMS/FS (n = 16) and healthy controls (HCs, n = 17) completed an abbreviated CANTAB battery, and measures of intellectual functioning, subjective cognitive complaints, performance validity, and comorbid symptoms. Subjective performance ratings were obtained to assess local metacognitive accuracy.

RESULTS

The groups were comparable in age (p = 0.45), sex (p = 0.62), IQ (p = 0.57), and performance validity (p-values = 0.10-0.91). We observed no impairment on any CANTAB test in this FMS/FS sample compared to HCs, although the FMS/FS group displayed shorter reaction times on the Emotional Bias task (anger) (p = 0.01, np2 = 0.20). The groups did not differ in subjective performance ratings (p-values 0.15). Whilst CANTAB attentional set-shifting performance (total trials/errors) correlated with subjective performance ratings in HCs (p-values<0.005, rs = -0.85), these correlations were non-significant in the FMS/FS sample (p-values = 0.10-0.13, rs-values = -0.46-0.50). The FMS/FS group reported more daily cognitive complaints than HCs (p = 0.006, g = 0.92), which were associated with subjective performance ratings on CANTAB sustained attention (p = 0.001, rs = -0.74) and working memory tests (p < 0.001, rs = -0.75), and with depression (p = 0.003, rs = 0.70), and somatoform (p = 0.003, rs = 0.70) and psychological dissociation (p-values<0.005, rs-values = 0.67-0.85).

CONCLUSIONS

These results suggest a discordance between objective and subjective neurocognitive functioning in this FMS/FS sample, reflecting intact test performance alongside poorer subjective cognitive functioning. Further investigation of neurocognitive functioning in FND subgroups is necessary.

Utility of CVLT-3 response bias as a measure of performance validity after traumatic brain injury

OBJECTIVE

We sought to determine the utility of a new performance validity index that was recently proposed. In particular, we wanted to determine if this index would be associated with a specificity of at least .90, a sensitivity of at least .40, and an Area Under the Curve of at least .70 in a traumatic brain injury (TBI) sample.

METHOD

We used logistic regression to investigate how well this new index could distinguish persons with TBI (n = 148) who were evaluated within 1-36 months after injury. All participants had been classified on the basis of at least two independent performance validity tests as having provided valid performance (n = 128) or invalid performance (n = 20).

RESULTS

The new performance validity index had acceptable specificity (.96) but had suboptimal sensitivity (.35) and Area Under the Curve (.66). It was concerning that almost half (5/12) of the cases that were identified by this index as providing invalid effort were false positives. Although a slightly more liberal cut-off improved sensitivity, the problem with poor positive predictive power remained. The conventional Forced Choice index had relatively better classification accuracy.

CONCLUSION

Differences in base rates between the original sample of Martin et al. and the current one most likely affected positive predictive power of the new index. Although their performance validity has excellent specificity, the current results do not support the application of this index in the clinical evaluation of patients with traumatic brain injury when base rates of invalid performance differ markedly from those in the original study.

The rate of psychiatric disorders in veterans undergoing intensive EEG monitoring is associated with symptom and performance invalidity

To determine if the number of participants with psychiatric disorders increased in association with failures on symptom validity tests (SVTs) and a performance validity test (PVT) in Veterans admitted for evaluation of possible seizures.

The 254 participants were Veterans undergoing inpatient video-EEG monitoring for the diagnosis of possible seizures. DSM-IV psychiatric disorders were diagnosed with the SCID IV. Symptom exaggeration was assessed with the MMPI-2-RF and performance validity with the TOMM.

On the MMPI-2-RF, 27.6%-32.7% showed symptom exaggeration. Participants who exaggerated on the MMPI-2-RF were more often diagnosed with psychiatric disorders. The TOMM was failed by 15.4% of the sample. Participants who failed the TOMM were more often diagnosed with an Axis I disorder but not with a personality disorder. The MMPI-2-RF was invalid in more cases than the TOMM, but 7.9% of the sample generated a valid MMPI-2-RF and an invalid TOMM.

The correlational design does not allow conclusions about cause and effect. The invalid groups may have had a higher rate of psychopathology. The number of participants with psychiatric disorders increased in association with symptom exaggeration and performance invalidity. Symptom exaggeration was more frequent than performance invalidity, but the TOMM made a unique contribution to identification of invalidity. The routine clinical use of SVTs and PVTs is supported. The results also suggest the need for caution in diagnosing psychiatric disorders when there is symptom exaggeration or performance invalidity, because diagnostic validity is dependent on the accuracy of symptom reporting.

Utility of the D-KEFS color word interference test as an embedded measure of performance validity after traumatic brain injury

ObjectiveWe sought to determine the accuracy of embedded performance measures for the D-KEFS Color Word Interference Test that were recently proposed by Eglit et al. In particular, we wanted to determine if these indices would be associated with a specificity of at least .90, an Area Under the Curve of at least .70 and a positive likelihood ratio of at least 2. Method: We used logistic regression to investigate how well these indices could distinguish persons with traumatic brain injury (n = 169) who were evaluated within 1-12 months after injury. All participants had been classified on the basis of at least three independent performance validity tests as valid performance (n = 145) or invalid performance (n = 24). Results: None of the three indices that Eglit et al. had proposed as embedded performance measures for the D-KEFS Color Word Interference Test achieved the a priori defined minimally acceptable level of specificity. One of them did meet the criteria for Area Under the Curve as well as positive likelihood ratio. Conclusion: The current results do not support the application of the Eglit et al. embedded performance validity measures for the D-KEFS Color Word Interference Test in the clinical evaluation of patients with traumatic brain injury.

BNT-15: Revised Performance Validity Cutoffs and Proposed Clinical Classification Ranges

BACKGROUND

Abbreviated neurocognitive tests offer a practical alternative to full-length versions but often lack clear interpretive guidelines, thereby limiting their clinical utility.

OBJECTIVE

To replicate validity cutoffs for the Boston Naming Test-Short Form (BNT-15) and to introduce a clinical classification system for the BNT-15 as a measure of object-naming skills.

METHOD

We collected data from 43 university students and 46 clinical patients. Classification accuracy was computed against psychometrically defined criterion groups. Clinical classification ranges were developed using a z -score transformation.

RESULTS

Previously suggested validity cutoffs (≤11 and ≤12) produced comparable classification accuracy among the university students. However, a more conservative cutoff (≤10) was needed with the clinical patients to contain the false-positive rate (0.20-0.38 sensitivity at 0.92-0.96 specificity). As a measure of cognitive ability, a perfect BNT-15 score suggests above average performance; ≤11 suggests clinically significant deficits. Demographically adjusted prorated BNT-15 T-scores correlated strongly (0.86) with the newly developed z -scores.

CONCLUSION

Given its brevity (<5 minutes), ease of administration and scoring, the BNT-15 can function as a useful and cost-effective screening measure for both object-naming/English proficiency and performance validity. The proposed clinical classification ranges provide useful guidelines for practitioners.

Neurocognitive Profiles Associated With Limited English Proficiency in Cognitively Intact Adults

OBJECTIVE

The objective of the present study was to examine the neurocognitive profiles associated with limited English proficiency (LEP).

METHOD

A brief neuropsychological battery including measures with high (HVM) and low verbal mediation (LVM) was administered to 80 university students: 40 native speakers of English (NSEs) and 40 with LEP.

RESULTS

Consistent with previous research, individuals with LEP performed more poorly on HVM measures and equivalent to NSEs on LVM measures-with some notable exceptions.

CONCLUSIONS

Low scores on HVM tests should not be interpreted as evidence of acquired cognitive impairment in individuals with LEP, because these measures may systematically underestimate cognitive ability in this population. These findings have important clinical and educational implications.

Neuropsychological performance and effort in patients diagnosed with psychogenic nonepileptic seizures - Descriptive study of a Czech sample

PURPOSE

The aim of the study was to examine the neuropsychological performance and effort in patients with a confirmed PNES diagnosis. The second aim of the study was to investigate the relationship between validity indicators from the cognitive battery with validity and clinical scales from a personality scale.

METHOD

Patients with PNES (N = 250; F:M 186:64; mean age 38.32 (13.23)) were assessed utilizing the RBANS (Czech Research version) to evaluate cognitive performance and to obtain the Effort Index. The MMPI-2 was used to evaluate personality and psychopathology.

RESULTS

Global cognitive performance was 0.92 SD below average (according to the Gaussian distribution) in patients with PNES. The lowest scores in the sample were in the Attention domain (-1.7SD). Insufficient effort was detected in 10% of patients. Education correlated negatively with the Effort index (rs = -0.25, p = 0.01). A mild significant correlation in Scale 7 (rs = 0.21, p = 0.01) and Scale 8 (rs = 0.24, p = 0.01), and a significant correlation between Effort Index and Back F Scale (rs = 0.23, p = 0.01) were noted.

CONCLUSIONS

Assessment of cognitive performance and effort is an essential part of the comprehensive evaluation of patients with PNES during their hospitalization at Epilepsy centers. Many aspects of the neuropsychological assessment can offer useful indications for reaching a differential diagnosis, including clinical history, behavioral observations, cognitive and symptom validity testing, and structured psychological inventories.

Failing Performance Validity Cutoffs on the Boston Naming Test (BNT) Is Specific, but Insensitive to Non-Credible Responding

This study was designed to examine alternative validity cutoffs on the Boston Naming Test (BNT).Archival data were collected from 206 adults assessed in a medicolegal setting following a motor vehicle collision. Classification accuracy was evaluated against three criterion PVTs.The first cutoff to achieve minimum specificity (.87-.88) was T ≤ 35, at .33-.45 sensitivity. T ≤ 33 improved specificity (.92-.93) at .24-.34 sensitivity. BNT validity cutoffs correctly classified 67-85% of the sample. Failing the BNT was unrelated to self-reported emotional distress. Although constrained by its low sensitivity, the BNT remains a useful embedded PVT.

Introducing the ImPACT-5: An Empirically Derived Multivariate Validity Composite

OBJECTIVE

To create novel Immediate Post-Concussion and Cognitive Testing (ImPACT)-based embedded validity indicators (EVIs) and to compare the classification accuracy to 4 existing EVIImPACT.

METHOD

The ImPACT was administered to 82 male varsity football players during preseason baseline cognitive testing. The classification accuracy of existing EVIImPACT was compared with a newly developed index (ImPACT-5A and B). The ImPACT-5A represents the number of cutoffs failed on the 5 ImPACT composite scores at a liberal cutoff (0.85 specificity); ImPACT-5B is the sum of failures on conservative cutoffs (≥0.90 specificity).

RESULTS

ImPACT-5A ≥1 was sensitive (0.81), but not specific (0.49) to invalid performance, consistent with EVIImPACT developed by independent researchers (0.68 sensitivity at 0.73-0.75 specificity). Conversely, ImPACT-5B ≥3 was highly specific (0.98), but insensitive (0.22), similar to Default EVIImPACT (0.04 sensitivity at 1.00 specificity). ImPACT-5A ≥3 or ImPACT-5B ≥2 met forensic standards of specificity (0.91-0.93) at 0.33 to 0.37 sensitivity. Also, the ImPACT-5s had the strongest linear relationship with clinically meaningful levels of invalid performance of existing EVIImPACT.

CONCLUSIONS

The ImPACT-5s were superior to the standard EVIImPACT and comparable to existing aftermarket EVIImPACT, with the flexibility to optimize the detection model for either sensitivity or specificity. The wide range of ImPACT-5 cutoffs allows for a more nuanced clinical interpretation.

The Comparison Between Neuropsychological Features of Psychogenic Non-epileptic Seizures and Epileptic Seizures

Background: Both epileptic seizures (ES) and psychogenic non-epileptic seizures (PNES) are often associated with some degree of cognitive impairment. Video electroencephalography (EEG) monitoring is the gold standard for diagnosing PNES. This diagnostic procedure is costly and available in specific tertiary centers. Neuropsychological assessment can provide clues for the differential diagnosis of PNES and ES and help clarify the nature and etiology of these two disorders. Objectives: Therefore, this study aimed to compare the neuropsychological profiles of PNES and ES patients. Methods: In this analytical cross-sectional study, 30 patients with ES and 31 patients with PNES were compared by neuropsychiatric tests, such as the Wechsler Adult Intelligence scale (WAIS), Addenbrooke’s Cognitive examination (ACE), and California Verbal Learning test (CVLT). Results: There was a female predominance in the PNES group (female-to-male ratio = 4.16/1, P = 0.003). In the PNES group, 77.4% of the patients had a psychiatric disorder versus 66.7% of the patients in the ES group; however, the difference was not statistically significant (P = 0.34). The mean score of total intelligence was higher in the PNES group (84.77 ± 16.94), compared to the ES group (83.63 ± 10.04); however, the difference was not significant (P = 0.75). Based on the mean subscale scores, the digit symbol score (WAIS-IV subscale) and memory score (ACE subscale) were significantly higher in the PNES group compared to the ES group (P = 0.037 and 0.032, respectively). Conclusions: This study showed that neuropsychological assessments might not differentiate ES from non-epileptic seizures.

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.

The emotion word fluency test as an embedded performance validity indicator - Alone and in a multivariate validity composite

OBJECTIVE

This project was designed to cross-validate existing performance validity cutoffs embedded within measures of verbal fluency (FAS and animals) and develop new ones for the Emotion Word Fluency Test (EWFT), a novel measure of category fluency.

METHOD

The classification accuracy of the verbal fluency tests was examined in two samples (70 cognitively healthy university students and 52 clinical patients) against psychometrically defined criterion measures.

RESULTS

A demographically adjusted T-score of ≤31 on the FAS was specific (.88-.97) to noncredible responding in both samples. Animals T ≤ 29 achieved high specificity (.90-.93) among students at .27-.38 sensitivity. A more conservative cutoff (T ≤ 27) was needed in the patient sample for a similar combination of sensitivity (.24-.45) and specificity (.87-.93). An EWFT raw score ≤5 was highly specific (.94-.97) but insensitive (.10-.18) to invalid performance. Failing multiple cutoffs improved specificity (.90-1.00) at variable sensitivity (.19-.45).

CONCLUSIONS

Results help resolve the inconsistency in previous reports, and confirm the overall utility of existing verbal fluency tests as embedded validity indicators. Multivariate models of performance validity assessment are superior to single indicators. The clinical utility and limitations of the EWFT as a novel measure are discussed.

Is sexual trauma a risk factor for functional (psychogenic) seizures?

The relationship between functional seizures (FS) and sexual trauma has received attention in many previous studies. However, the mechanisms underlying this relationship have not been elucidated yet. The purpose of this narrative review is to explore and speculate on the underpinning neurobiological mechanisms for the association and link between sexual trauma and functional seizures. While existence of a causal relationship between a history of sexual trauma and functional seizures is plausible, it should be viewed and treated as a hypothesis. In explaining this hypothesis, we can speculate that interactions between genetic factors and a history of sexual trauma may contribute to the risk of experiencing functional seizures. Childhood sexual trauma may lead to structural and functional connectivity changes in the brain and dysregulation of the biological stress systems, particularly in women. These neurobiological changes speculatively may predispose patients to functional seizures later in life. Importantly, a history of sexual trauma has many other implications beyond the predisposition towards FS.

Flipping the Script: Measuring Both Performance Validity and Cognitive Ability with the Forced Choice Recognition Trial of the RCFT

In this study we attempted to replicate the classification accuracy of the newly introduced Forced Choice Recognition trial (FCR) of the Rey Complex Figure Test (RCFT) in a clinical sample. We administered the RCFT_FCR and the earlier Yes/No Recognition trial from the RCFT to 52 clinically referred patients as part of a comprehensive neuropsychological test battery and incentivized a separate control group of 83 university students to perform well on these measures. We then computed the classification accuracies of both measures against criterion performance validity tests (PVTs) and compared results between the two samples. At previously published validity cutoffs (≤16 & ≤17), the RCFT_FCR remained specific (.84-1.00) to psychometrically defined non-credible responding. Simultaneously, the RCFT_FCR was more sensitive to examinees' natural variability in visual-perceptual and verbal memory skills than the Yes/No Recognition trial. Even after being reduced to a seven-point scale (18-24) by the validity cutoffs, both RCFT recognition scores continued to provide clinically useful information on visual memory. This is the first study to validate the RCFT_FCR as a PVT in a clinical sample. Our data also support its use for measuring cognitive ability. Replication studies with more diverse samples and different criterion measures are still needed before large-scale clinical application of this scale.

RBANS Validity Measures and the TOMM in Veterans Undergoing Seizure Monitoring

OBJECTIVE

To assess the validity of embedded measures of performance validity, the effort index (EI) and effort scale (ES) of the repeatable battery for the assessment of neuropsychological status (RBANS), in Veterans with seizures; to compare the frequency of failure on the test of memory malingering (TOMM) in patients with epileptic versus psychogenic nonepileptic seizures (PNES).

METHODS

Seizure diagnosis was established for 309 participants in epilepsy monitoring units using conventional diagnostic criteria who completed both the TOMM and RBANS. The criterion for performance invalidity was failure on any trial of the TOMM. We examined multiple EI and ES cutoffs to establish optimal sensitivity and specificity.

RESULTS

An RBANS EI cutoff score of greater than three was optimal with specificity of .98, sensitivity of.19, and positive Likelihood Ratio of 10 but was not useful when below this cutoff. Confidence intervals indicate the need for confirmation of a failed EI with another performance validity test (PVT). No ES cutoff had sufficient specificity for clinical use. Invalid TOMM performance but not invalid RBANS performance was significantly more common in persons with PNES than in persons with epileptic seizures.

CONCLUSIONS

In Veterans undergoing seizure monitoring, the RBANS EI was useful as a screen when positive that requires confirmation with another PVT. The RBANS ES was not useful. Invalid performance on the TOMM was more common in persons with PNES than in persons with epileptic seizures.

Psychiatric comorbidities in patients with psychogenic nonepileptic seizures

BACKGROUND

Psychogenic nonepileptic seizures (PNES) are major challenges for diagnosis and management. The heterogeneity of psychogenic seizures is attributed to diverse psychopathological comorbidities, and the causal relationship between PNES and underlying psychopathologies is still enigmatic.

OBJECTIVE

Our objective was to study psychiatric comorbidities and personality constructs in patients with PNES and compare them to a control group of patients with epilepsy.

METHOD

We randomly recruited 33 patients with PNES and 33 patients with epilepsy. All patients completed the Mini-International Neuropsychiatric Interview (MINI) to screen for psychiatric comorbidities, the Structured Clinical Interview for psychiatric disorders in Axis II (SCID II) to screen for personality disorders, and Goldberg's International Personality Item Pool (IPIP) Big Five personality questionnaire to study the psychological constructs of extroversion-introversion, agreeableness, conscientiousness, emotional stability-neuroticism, and intellect.

RESULT

Mood and anxiety disorders were highly prevalent in patients with PNES (72.7% and 54.5%, respectively); however, the prevalence of only cluster B personality disorder was higher in patients with PNES (69.7%) compared to 33.3% among patients with epilepsy (p < 0.05). Screening for personality disorders using SCID II showed that the prevalence of borderline and depressive personality disorders was significantly higher in patients with PNES (p < 0.001). Patients with psychogenic seizures were more likely to be receiving polydrug therapy (75.8%) compared to patients with epileptic seizures (45.5%); this difference was statistically significant (p < 0.05).

CONCLUSION

Psychiatric comorbidities are highly prevalent among patients with PNES.

Psychogenic nonepileptic seizures: The effect of accurate diagnosis on cognition

OBJECTIVE

Much remains to be elucidated about the cognitive profile of patients with psychogenic nonepileptic seizures (PNES) and about how this changes over time and compares to that of patients with epilepsy. The aim of this study was to study the neuropsychological profile of patients with PNES and an age-matched group of patients with temporal lobe epilepsy (TLE) during admission to a video electroencephalography monitoring unit (VEMU) and 1 year after discharge.

METHODS

Patients diagnosed with PNES or TLE at a VEMU were prospectively recruited. Neuropsychological, demographic, clinical, and treatment variables were collected at baseline and 1 year. To minimize multiple comparisons, scores from different cognitive tests were computed for attention and psychomotor speed, verbal memory, visual memory, language, and executive function. A global cognitive impairment index (GCII) was also created. Post hoc analyses were conducted to identify clinical variables that might mediate the differences observed in cognition over time between the groups. These included seizure frequency, number of antiseizure medication (ASM), number of psychotropic drugs, depression, and quality of life.

RESULTS

We studied 24 patients with PNES and 24 patients with TLE. The groups performed similarly in the baseline neuropsychological tests. There was a significant time (baseline to 1-year follow-up) by group (PNES vs TLE) interaction for the GCII (p = 0.006), language (p = 0.04), and executive function (p = 0.013), with PNES patients showing improvement and TLE patients remaining stable. The time by group interaction for attention and psychomotor speed showed a trend toward significance (p = 0.056), Reduction in number of ASM was associated with improved cognition in PNES patients at 1 year.

CONCLUSION

PNES patients showed improved cognition at 1 year of follow-up, particularly in language and executive functions. This finding shows the potential benefits of an early, accurate diagnosis, which range from improved cognition to better management.

Predictive utility of the Minnesota Multiphasic Personality Inventory-2-RF (MMPI-2-RF) in differentiating psychogenic nonepileptic seizures and epileptic seizures in male veterans

OBJECTIVE

While psychogenic nonepileptic seizures (PNES) and epileptic seizures (ES) often present similarly, they are etiologically distinct, and correct diagnosis is essential for ensuring appropriate treatment and improving outcomes. The Minnesota Multiphasic Personality Inventory-2-RF (MMPI-2-RF) may assist in differential diagnosis, but prior investigations have been limited by disproportionately female samples, inconsistent accounting for profile invalidity, and limited intra-scale variability from dichotomizing variables. The current investigation addressed these gaps by assessing diagnostic utility of the MMPI-2-RF in differentiating PNES and ES in a male sample of veterans while conservatively accounting for profile invalidity and using a statistical approach that allows for consideration of continuous independent variables to better appreciate intra-scale variance.

METHOD

One hundred and forty-four veterans completed the MMPI-2-RF and were diagnosed with PNES (57.6%) or ES (42.4%) by a board-certified neurologist following continuous video-EEG monitoring. Participants with validity scores falling in the definitely or likely invalid ranges were excluded to ensure construct validity among clinical/substantive scales. Independent samples t-tests assessed differences in MMPI-2-RF variables by diagnostic groups. Hierarchical stepwise logistical regressions assessed predictive utility of MMPI-2-RF indices. A clinical calculator was derived from regression findings to help with diagnostic prediction.

RESULTS

Males with PNES endorsed significantly higher scores on F-r, FBS-r, RBS, RC1, RC7, HPC, and NUC (medium to large effect sizes). The regression block that contained validity, restructured clinical (RC1), and substantive scales (GIC, SUI) had a hit rate of 75.69%, which was an improvement from the baseline model hit rate of 57.64%. Higher endorsement on RC1 and lower reporting on GIC significantly predicted PNES diagnosis for males.

CONCLUSIONS

Minnesota Multiphasic Personality Inventory-2-RF improved diagnostic accuracy of PNES versus ES among male veterans, and RC1 (somatic complaints) emerged as a significant predictor for males with PNES, in line with hypotheses. Several clinical/substantive scales assisted with differential diagnosis after careful accounting for profile validity. Future studies can validate findings among males outside of veteran samples.

Clinical identification of psychogenic nonepileptic events using combinations of psychological tests in a veteran sample

OBJECTIVE

Patients with psychogenic nonepileptic events (PNEE) exhibit heterogenous symptoms and are best diagnosed with long-term video-electroencephalogram (vEEG) data. While extensive univariate data suggest psychological tests may confirm the etiology of PNEE, the multivariate discriminant utility of psychological tests is less clear. The current study aggregated likelihood ratios of multiple psychological tests to evaluate incremental and discriminant utility for PNEE.

METHODS

Veterans with vEEG-diagnosed PNEE (n = 166) or epileptic seizures (n = 92) completed self-report measures and brief neuropsychological evaluations during the 4-day vEEG hospitalization. Receiver operating characteristic (ROC) curves identified discriminating psychological tests and corresponding cut-scores (0.85 minimum specificity). Likelihood ratios from the remaining cut-scores were sequentially linked using the sample base rate of PNEE (64%) and alternative base rates (10%, 20%, 30%, 40%) to estimate posttest probabilities (PTP) of test combinations.

RESULTS

The Health Attitudes Survey, Health History Checklist, and Minnesota Multiphasic Personality Inventory-2-Restructured Form scales FBS-r, RC1, MLS, and NUC were identified as discriminating indicators of PNEE. Average PTPs were ≥90% when three or more indicators out of six administered were present at the sample base rate. Regardless of PNEE base rate, PTP for PNEE was ≥98% when all discriminating indicators were present and 92-99% when five of six indicators administered were present. PTPs were largely consistent with observed positive predictive values, particularly as indicators present increased.

SIGNIFICANCE

Aggregating psychological tests identified PNEE with a high degree of accuracy, regardless of PNEE base rate. Combining psychological tests may be useful for confirming the etiology of PNEE.

Ictal level of awareness in psychogenic nonepileptic seizures correlates with the experience of traumatic events in childhood: A cross sectional study

There is a great amount of research regarding the particular ictal manifestations of psychogenic nonepileptic seizures (PNES) with a focus on the differences to epileptic seizures (Vogrig et al., 2019 [4]; Tyson et al., 2018 [5]; De Paola et al., 2016 [6]). Most of the research aims to define guidelines for diagnosing PNES in differentiation from epilepsy, because this differentiation is clinically relevant for clinical neurological settings. In contrast, very few studies aimed to gain insight about particular ictal manifestations of the different semiological appearances of PNES regarding distinctive psychological processes or prognostic outcomes (Brown, 2016 [7]; Pick et al., 2017 [8]; Brown, 2006 [9]; Cohen, 2013). One study revealed that a higher level of mental dissociation and cognitive impairment was associated with a higher level of traumatization in patients with PNES (Pick et al., 2017 [8]). We analyzed the seizure semiology with a focus on the level of awareness in 60 patients with PNES. Patients were divided into two groups: one with an impaired awareness during their seizures and the other one with preserved awareness during their seizures. We assessed the amount of adverse traumatic experience in childhood with the "Childhood Trauma Questionnaire (CTQ)". We found that patients with PNES with impaired awareness showed more childhood traumatic experiences in the CTQ, especially on the subscales of sexual and emotional abuse as well as physical neglect. Furthermore, patients with PNES with impaired awareness during seizures were significantly younger, more often female, showed a lower degree on education, and a higher amount of self-harm behavior compared with patients with PNES with preserved awareness during seizures. Our study presents clinical evidence for the potential significance of the level of awareness during PNES for the etiology of PNES. Our results point toward the existence of clinical subgroups of patients with PNES with distinctive etiological mechanisms and indicate that seizure semiology might help to differentiate those potential subgroups.

Neurochemicals of limbic system and thalamofrontal cortical network: Are they different between patients with idiopathic generalized epilepsy and psychogenic nonepileptic seizure?

OBJECTIVE

Thalamofrontal cortical network and limbic system are proposed to be involved in psychogenic nonepileptic seizure (PNES) and idiopathic generalized epilepsy (IGE). This study aimed to investigate neurochemical changes in prefrontal cortex, thalamus, and limbic circuits in patients with PNES and IGE. We also analyzed the interaction between cognitive functions and neurochemical changes in both groups.

METHODS

Hydrogen proton magnetic resonance spectroscopy (1H-MRS) was used to measure N-acetyl aspartate (NAA), choline (Cho), creatine (Cr), glutamate-glutamine (Glx), and myo-inositol (MI). The voxels were placed on the bilateral dorsolateral prefrontal cortex (DLPFC), dorsomedial prefrontal cortex (DMPFC), anterior cingulate cortex (ACC), and thalamus. Attention and inhibitory control, as well as general intelligence status, were investigated using the Integrated Visual and Auditory Continuous Performance Test (IVA-CPT) and the Wechsler Adult Intelligence Scale (WAIS), respectively, in patients with PNES and IGE, as well as healthy volunteers.

RESULTS

The 1H-MRS showed a decreased ratio of NAA/Cr in the right and left thalamus, right DMPFC, and right ACC in patients with IGE and PNES. Furthermore, a decrease of the NAA/Cr ratio in the left DMPFC and an increase of NAA/Cr ratio in the right DLPFC were observed in patients with PNES compared with the controls. The patient groups had a decreased ratio of Cho/Cr in right ACC compared with the healthy subjects. Moreover, the NAA/Cr ratio in the left thalamus and left DMPFC was correlated with seizure frequency in patient groups. Reduced NAA/Cr ratio in the right ACC and left DLPFC were also correlated with poor IVA-CPT scores.

CONCLUSION

This study highlighted the dysfunction in prefrontal-thalamic-limbic circuits and impairment in neurocognition in patients with PNES and IGE.

Validity testing in veterans with epileptic seizures and psychogenic nonepileptic seizures

OBJECTIVE

Identification of clinically meaningful subgroups among patients with psychogenic nonepileptic seizures (PNES) or epileptic seizures (ES) is of potential value for assessing prognosis and predicting therapeutic response. Invalid performance on validity tests has been associated with noncredible complaints and worse cognitive test scores, and may be one such classification criteria. We studied invalid performance in Veterans with PNES or ES, and the association of invalid performance with cognitive test scores and subjective complaints.

METHODS

Patients were consecutive admissions to three veterans affairs (VA) epilepsy monitoring units. Evaluations included two validity tests: the Test of Memory Malingering (TOMM); and the Minnesota Multiphasic Personality Inventory-2-Restructured Form (MMPI-2-RF) over-reporting validity scales. We compared the frequency of invalid performance on the TOMM or MMPI-2-RF in patients diagnosed with PNES vs. ES. We evaluated the association of invalid performance with scores on the Repeatable Battery for Assessment of Neuropsychological Status (RBANS), and four subjective symptom measures including the Beck Depression Inventory-II, and Quality of Life in Epilepsy-31.

RESULTS

Invalid TOMM performance was found in 25.3% of Veterans diagnosed with PNES and 10.8% of those with ES (p = .03). Invalid reporting on the MMPI-2-RF was found in 35.9% of the PNES group vs. 15.3% of the ES group (p = .01). Effects of valid vs. invalid reporting on external measures were similar for ES and PNES groups. Patients with invalid vs. valid TOMM performance had lower scores on the RBANS (p < .001). Patients with invalid performance had greater complaints on all subjective measures, with largest effect sizes for the MMPI-2-RF validity scales (p < .001).

SIGNIFICANCE

In Veterans admitted for evaluation of poorly controlled seizures, invalid performance on validity tests was not uncommon. Cognitive test results and subjective reports from patients with invalid performance may not be credible. These observations have implications for the analysis of clinical trials, where primary and secondary outcomes often rely on self-report measures.

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.

Performance validity test failure in clinical populations-a systematic review

Performance validity tests (PVTs) are widely used in attempts to quantify effort and/or detect negative response bias during neuropsychological testing. However, it can be challenging to interpret the meaning of poor PVT performance in a clinical context. Compensation-seeking populations predominate in the PVT literature. We aimed to establish base rates of PVT failure in clinical populations without known external motivation to underperform. We searched MEDLINE, EMBASE and PsycINFO for studies reporting PVT failure rates in adults with defined clinical diagnoses, excluding studies of active or veteran military personnel, forensic populations or studies of participants known to be litigating or seeking disability benefits. Results were summarised by diagnostic group and implications discussed. Our review identified 69 studies, and 45 different PVTs or indices, in clinical populations with intellectual disability, degenerative brain disease, brain injury, psychiatric disorders, functional disorders and epilepsy. Various pass/fail cut-off scores were described. PVT failure was common in all clinical groups described, with failure rates for some groups and tests exceeding 25%. PVT failure is common across a range of clinical conditions, even in the absence of obvious incentive to underperform. Failure rates are no higher in functional disorders than in other clinical conditions. As PVT failure indicates invalidity of other attempted neuropsychological tests, the finding of frequent and unexpected failure in a range of clinical conditions raises important questions about the degree of objectivity afforded to neuropsychological tests in clinical practice and research.

Epileptic seizures

Epilepsy is a condition marked by abnormal neuronal discharges or hyperexcitability of neurons with synchronicity and is recognized as a major public health concern. The pathology is categorized into three subgroups: acquired, idiopathic, and epilepsy of genetic or developmental origin. There are approximately 1000 associated genes and the role of γ-aminobutyric acid (GABA) mediated inhibition, as well as glutamate mediated excitation, forms the basis of pathology. Epilepsy is further classified as being of focal, general or unknown onset. Genetic predisposition, comorbidities and novel biomarkers are useful for prediction. Prevalent postictal symptoms are postictal headache and migraine, postictal psychosis and delirium, postictal Todd's paresis and postictal automatisms. Diagnostic methods include electroencephalography (EEG), computed tomography scan, magnetic resonance imaging (MRI), positron emission tomography, single photon emission computed tomography and genetic testing; EEG and MRI are the two main techniques. Clinical history and witness testimonies combined with a knowledge of seizure semiology helps in distinguishing between seizures. Clinical information and patient history do not always lead to a clear diagnosis, in which case EEG and 24-hour EEG monitoring with video recording (video-EEG/vEEG) help in seizure differentiation. Treatment includes first aid, therapeutics such as anti-epileptic drugs, surgery, ketogenic diet and gene therapy. In this review, we are focusing on summarizing published literature on epilepsy and epileptic seizures, and concisely apprise the reader of the latest cutting-edge advances and knowledge on epileptic seizures.

Short-term effects of cannabis consumption on cognitive performance in medical cannabis patients

This observational study examined the acute cognitive effects of cannabis. We hypothesized that cognitive performance would be negatively affected by acute cannabis intoxication. Twenty-two medical cannabis patients from Southwestern Ontario completed the study. The majority (n = 13) were male. Mean age was 36.0 years, and mean level of education was 13.7 years. Participants were administered the same brief neurocognitive battery three times during a six-hour period: at baseline ("Baseline"), once after they consumed a 20% THC cannabis product ("THC"), and once again several hours later ("Recovery"). The average self-reported level of cannabis intoxication prior to the second assessment (i.e., during THC) was 5.1 out of 10. Contrary to expectations, performance on neuropsychological tests remained stable or even improved during the acute intoxication stage (THC; d: .49-.65, medium effect), and continued to increase during Recovery (d: .45-.77, medium-large effect). Interestingly, the failure rate on performance validity indicators increased during THC. Contrary to our hypothesis, there was no psychometric evidence for a decline in cognitive ability following THC intoxication. There are several possible explanations for this finding but, in the absence of a control group, no definitive conclusion can be reached at this time.