Charles W. Mathias

Symptom Validity Testing: A Critical Review

This paper provides a comprehensive review of the published literature on symptom validity tests (SVT) and, with the accompanying tables, serves as a reference to assist in their selection, interpretation, and defense. Because malingering is inherently an applied problem that frequently arises in a medico-legal context, the use of SVTs must meet certain standards. Thus, a number of methodological and theoretical weaknesses of SVT research which limit the use of SVTs as clinical tools and sources of evidence are highlighted. These criticisms incorporate recommendations which must be addressed if conclusions based on SVT data are to meet the increasingly rigorous standards for the admissibility of scientific evidence.

Impulsiveness and risk-taking behavior: comparison of high-school and college students using the Barratt Impulsiveness Scale

The present study was undertaken in an attempt to determine the relationship of impulsiveness to risk-taking behaviors such as aggression, drug use, drunk driving and not wearing seatbelts among highschool and college students. The results of the study clearly demonstrate that high impulsives are involved in risk-taking behavior at a higher rate than low impulsive subjects. These findings suggest that high impulsive adolescents and young adults are at considerable risk of personal injury and present a potential source of injury to others. It is suggested that self-report questionnaires of impulsiveness might prove useful in the early identification of these high risk individuals. Once identified these individuals could be targeted for intensive educational interventions specifically designed to deal with their inability to delay gratification and general lack of impulse control. Language: en

Personality and neurocognitive correlates of impulsive aggression in long-term survivors of severe traumatic brain injury

This study addresses a common outcome of severe traumatic brain injury (TBI), disinhibited aggressive behaviour. This behaviour has been classified in aggression literature as impulsive aggression (IA). The purpose was to: (1) characterize those TBI patients who are likely to be an aggression risk, and (2) determine if TBI patients with IA demonstrate personality style and neurocognitive performance similar to that seen in other IA groups. Participants were 45 survivors of severe TBI (26 of whom had persisting problems with IA), who were clients of a residential brain injury treatment facility. IA participants had a higher incidence of pre-morbid aggressive behaviour, were younger, had a shorter tenure in the programine, and were more impulsive, irritable, and antisocial than the non-aggressive control participants. Unlike past research, no neurocognitive differences were found. The results are discussed in terms of the conceptualization, identification, and treatment of persisting IA in severe TBI.This study addresses a common outcome of severe traumatic brain injury (TBI), disinhibited aggressive behaviour. This behaviour has been classified in aggression literature as impulsive aggression (IA). The purpose was to: (1) characterize those TBI patients who are likely to be an aggression risk, and (2) determine if TBI patients with IA demonstrate personality style and neurocognitive performance similar to that seen in other IA groups. Participants were 45 survivors of severe TBI (26 of whom had persisting problems with IA), who were clients of a residential brain injury treatment facility. IA participants had a higher incidence of pre-morbid aggressive behaviour, were younger, had a shorter tenure in the programme, and were more impulsive, irritable, and antisocial than the non-aggressive control participants. Unlike past research, no neurocognitive differences were found. The results are discussed in terms of the conceptualization, identification, and treatment of persisting IA in severe TBI.

Detecting malingered performance on the Wechsler Adult Intelligence Scale: Validation of Mittenberg's approach in traumatic brain injury

This study assesses the effectiveness of the Wechsler Adult Intelligence Scale (WAIS) performance validity markers devised by Mittenberg et al. [Prof. Psychol.: Res. Pract. 26 (1995) 491] in the detection of malingered neurocognitive dysfunction (MND). Subjects were 65 traumatic brain injury (TBI) patients referred for neuropsychological evaluation. Twenty-eight met the Slick et al. [Clin. Neuropsychol. 13 (1999) 545] criteria for at least probable MND. The control group was comprised of 37 patients without external incentive and who thus did not meet the Slick et al. criteria. All subjects completed the Wechsler Adult Intelligence Scale-Revised (WAIS-R or WAIS-III). The discriminant function score (DFS) and the vocabulary-digit span (VDS) difference score were calculated and sensitivity, specificity, and predictive power were examined for several cut-offs for each marker individually and the two combined. Classification accuracy for the DFS was acceptable and better than for VDS. The use of the two markers in combination resulted in no incremental increase in classification accuracy. Issues related to the clinical application of these techniques are discussed.

Detecting Malingered Performance With the Wisconsin Card Sorting Test: A Preliminary Investigation in Traumatic Brain Injury

The present study examined the classification accuracy of four potential Wisconsin Card Sorting Test malingering indicators (Bernard and Suhr formulas and two types of Unique responses). Participants were 89 traumatic brain-injury (TBI) patients assigned to malingering and nonmalingering groups on the basis of the Slick, Sherman, and Iversion (1999) criteria. Individual Sensitivities were greater than .33 with acceptable Specificity. Combined Sensitivity for two of the indicators was greater than .60. Overall, this study demonstrated three distinct approaches to the WCST used by probable malingerers. The clinical relevance of these findings and directions for future research are discussed.

Wisconsin Card Sorting Test in chronic severe traumatic brain injury: factor structure and performance subgroups

Objective : The present study further investigated the factor structure of the WCST in traumatic brain injury and investigated the construct validity and relationships among scores through the use of cluster analysis. Design : Participants were 68 survivors of chronic severe TBI, living at a residential brain injury rehabilitation facility. Methods and procedures : Three sets of WCST scores were submitted to factor analysis; the regression factor scores based on the standard WCST were examined using cluster analysis. Results : Factor analysis of the WCST raw scores replicated the three-factor solution which has been previously reported. When t -scores were analysed, two-to-four-factor solutions could be justified. The cluster analysis identified four groups representing: (1) impaired response maintenance; (2) problem-solving deficits; (3) intact WCST performance; and (4) deficits in set shifting. Conclusions : The results support previous research indicating that the WCST is sensitive to three distinct cognitive processes: cognitive flexibility, problem-solving, and response maintenance. However, unlike the cognitive processes underlying WCST performance, the WCST scores representing these processes are not independent. The potential clinical relevance of these results is discussed.

P300 under standard and surprise conditions in self-reported impulsive aggression

1. The purpose of the present study was to determine the cognitive psychophysiological correlates of impulsive aggression in a high functioning sample: college students. 2. Visual P300 was measured during a standard oddball task and a surprise task that included unexpected low probability stimuli. 3. Results indicated significantly reduced P300 amplitude and prolonged latency for impulsive aggressive subjects to target stimuli on the standard task. Target amplitude differences where further augmented under conditions involving unexpected stimuli although no significant latency differences were observed. The topography of P300 amplitude to unexpected stimuli differed from that of the target. 4. Topographic group differences found for unexpected stimuli are suggestive of cognitive processing deficits previously demonstrated using neuropsychological techniques in impulsive aggressive individuals.

AUDITORY P300 AND SELF'-REPORTED IMPULSIVE AGGRESSION

1. The purpose of the present study was to determine the cognitive psychophysiological correlates of impulsive aggression in a population considered normal by societal standards: college students. 2. Auditory event-related potentials were acquired on all subjects during a standard oddball task. The stimuli consisted of a random sequence of two tones, a frequent 1,000 Hz tone and a rare 2,000 Hz tone. Tones were presented in a ratio of 80/20. 3. Results of the study demonstrated that impulsive aggressive subjects show significantly lower P300 amplitude at frontal electrode sites when compared to nonaggressive controls. 4. These findings are consistent with the psychophysiological findings in impulsive aggressive incarcerated criminals and support the notion of a specific behavioral syndrome associated with spontaneous aggressive outbursts.

Paced Visual Serial Addition Test: An Alternative Measure of Information Processing Speed

The Paced Auditory Serial Addition Test (PASAT; Gronwall, 1977; Gronwall & Sampson, 1974) is a measure of attention and information processing speed sensitive to mild traumatic brain injury (MTBI), but it is aversive and inappropriate for many other neurologically impaired patients. This study examines a simpler, less aversive visual analog of the PASAT (the Paced Visual Serial Addition Test; PVSAT) in a sample of 74 college students (26 with a history of TBI). Results indicated that the PVSAT is moderately correlated with and less difficult than the PASAT. Both tests had identical relations to other measures of attention. Neither the PVSAT, PASAT, nor the other attentional measures differentiated participants with MTBI from normal controls in a college population. This preliminary study thus demonstrates the comparability of the two tests and presents the PVSAT as a viable alternative to the PASAT. Directions for future research and applications of these findings are discussed.

Classification Accuracy of the Portland Digit Recognition Test in Traumatic Brain Injury

This study examined the classification accuracy of the Portland Digit Recognition Test (PDRT) in traumatic brain injury (TBI). It differs from past studies in assigning patients to malingering and control groups on the basis of compensation-seeking status and the presence of external markers for malingering. Sensitivity and Specificity were .77 and 1.00, respectively. Past research comparing compensation-seekers to noncompensation-seekers reported Sensitivities of .33 or lower (Specificity is always high). This study demonstrates that past research has seriously underestimated the Sensitivity of the PDRT and raises questions about the true Sensitivity of other malingering techniques as well.