Joseph L. Etherton

Detecting Malingered Pain-Related Disability: Classification Accuracy of the Test of Memory Malingering

This study used criterion groups validation to determine the accuracy of the Test of Memory Malingering (TOMM) in detecting malingered pain-related disability (MPRD) across a range of cutoffs in chronic pain patients undergoing psychological evaluation (n = 604). Data from patients with traumatic brain injury (n = 45) and dementia (n = 59) are presented for comparison. TOMM scores decreased and failure rates increased as a function of greater external evidence of intentional under-performance. The TOMM detected from 37.5% to 60.2% of MPRD patients, depending on the cutoff. False positive (FP) error rates ranged from 0% to 5.1%. Accuracy data for Trial 1 are also reported. In chronic pain the original cutoffs produced no FP errors but were associated with high false negative error rates. Higher cutoffs increased sensitivity without adversely affecting specificity. The relevance of these findings to research and clinical practice is discussed.

The Reliable Digit Span test in chronic pain: classification accuracy in detecting malingered pain-related disability.

This study used criterion groups validation (known-groups design) to examine the classification accuracy of the Reliable Digit Span test (RDS) in a large group of chronic pain patients referred for psychological evaluation. The sample consisted of 612 patients classified into one of six groups based on evidence of malingered pain-related disability (MPRD): No-Incentive, Not MPRD; Incentive-Only, Not MPRD; Indeterminate; Possible MPRD; Probable MPRD; Definite MPRD. A total of 30 college student simulators were also included. Lower average RDS scores and higher rates of RDS failure were seen in patients classified as MPRD and in simulators. Consistent with previous literature in a variety of populations, RDS < = 6 provided the most accurate differentiation between MPRD and non-MPRD pain patients. Clinical implications are discussed.

Individual and Gender Differences in Subjective and Objective Indices of Pain: Gender, Fear of Pain, Pain Catastrophizing and Cardiovascular Reactivity

According to fear-avoidance models of pain perception, heightened fear of pain may increase disruptive effects of pain; however, the extent to which this affects self-reported pain severity versus physiological indices of pain is not well delineated. The current study examined self-report measures and physiological indices of pain during a cold pressor (CP) task. Individual differences in fear of pain and pain catastrophizing were also assessed via questionnaire. The primary aim of the current study was to examine the extent to which individual differences associated with fear and catastrophizing in response to pain influences subjective and physiological measures of pain. A secondary aim was to examine gender differences associated with response to pain. Average subjective pain ratings were higher for females than males. In contrast, males exhibited higher systolic and diastolic reactivity in response to the CP task relative to females, as well as failure to fully recover to baseline levels. Follow-up correlational analyses revealed that subjective pain ratings were positively associated with fear of pain in both sexes, but were not associated with cardiovascular indices. These results suggest that fear of pain and pain catastrophizing do not influence cardiovascular responses to induced pain. Further research is necessary in order to determine whether these gender differences in blood pressure and heart rate response profiles are due to biological or psychosocial influences. Results support the notion that fear of pain increases subjective pain ratings, but does not influence cardiovascular responses during CP pain-induction.

Detecting Malingered Pain-Related Disability: Classification Accuracy of the Portland Digit Recognition Test

This study used criterion groups validation to determine the classification accuracy of the Portland Digit Recognition Test (PDRT) at a range of cutting scores in chronic pain patients undergoing psychological evaluation ( n = 318), college student simulators ( n = 29), and patients with brain damage ( n = 120). PDRT scores decreased and failure rates increased as a function of greater independent evidence of intentional underperformance. There were no differences between patients classified as malingering and college student simulators. The PDRT detected from 33% to nearly 60% of malingering chronic pain patients, depending on the cutoff used. False positive error rates ranged from 3% to 6%. Scores higher than the original cutoffs may be interpreted as indicating negative response bias in patients with pain, increasing the usefulness and facilitating the clinical application of the PDRT in the detection of malingering in pain.

Accuracy of the Modified Somatic Perception Questionnaire and Pain Disability Index in the Detection of Malingered Pain-Related Disability in Chronic Pain

The Modified Somatic Perception Questionnaire (MSPQ) and the Pain Disability Index (PDI) are both popular clinical screening instruments in general orthopedic, rheumatologic, and neurosurgical clinics and are useful for identifying pain patients whose physical symptom presentations and disability may be non-organic. Previous studies found both to accurately detect malingered pain presentations; however, the generalizability of these results is not clear. This study used a criterion groups validation design (retrospective cohort of patients with chronic pain, n = 328) with a simulator group (college students, n = 98) to determine the accuracy of the MSPQ and PDI in detecting Malingered Pain Related Disability. Patients were grouped based on independent psychometric evidence of MPRD. Results showed that MSPQ and PDI scores were not associated with objective medical pathology. However, they accurately differentiated Not-MPRD from MPRD cases. Diagnostic statistics associated with a range of scores are presented for application to individual cases. Data from this study can inform the clinical management of chronic pain patients by screening for psychological overlay and malingering, thus alerting clinicians to the possible presence of psychosocial obstacles to effective treatment and triggering further psychological assessment and/or treatment.

Cold Pressor-Induced Pain Does Not Impair WAIS-IV Processing Speed Index or Working Memory Index Performance

Chronic pain frequently involves cognitive complaints such as concentration and memory deficits, but studies of the effects of pain on cognition have not consistently demonstrated deficits and have not typically utilized standard neuropsychological instruments. Effects of cold pressor-induced pain on Wechsler Adult Intelligence Scale-Fourth Edition Processing Speed Index (PSI) and Working Memory Index (WMI) performance was examined in nonclinical volunteers (n = 40). All took one PSI subtest and one WMI subtest normally, and then took different PSI and WMI subtests during cold pressor-induced pain or painless warm-water immersion. Scaled scores for normal administration versus pain or painless water immersion did not differ and there was no interaction between group (control vs. pain) and manner of administration, despite moderately severe mean pain ratings (M = 6.8 on a 0–10 pain-rating scale). Results indicate that induced pain in nonclinical volunteers does not impair PSI or WMI performance, and they suggest that chronic pain per se should not be expected to substantially affect these cognitive functions. However, patients with chronic pain may differ from nonclinical volunteers in their experience of pain, potentially limiting generalizability.

Do Administration Instructions Alter Optimal Neuropsychological Test Performance? Data From Healthy Volunteers

The degree to which patients should be prompted to give their best effort has not been adequately addressed in the literature, nor has the issue of the extent to which they should be informed that measures of effort will be included in the assessment battery. Three groups of undergraduates were given three different instructional sets prior to completing a neuropsychological evaluation. The instructions provided different levels of motivation to perform optimally as well as possible warning regarding the detection of poor effort. The three groups did not differ in performance on any of the cognitive measures, although outlier performance resulted in lower mean performance on the Finger Tapping Test by the most clearly warned group. The results are discussed in terms of the potential of different instructional sets to affect motivation for optimal test performance.

Performance on selected visual and auditory subtests of the Wechsler Memory Scale-Fourth Edition during laboratory-induced pain

Although chronic pain patients commonly report problems with concentration and memory, recent research indicates that induced pain alone causes little or no impairment on several Wechsler Adult Intelligence Scale–Fourth Edition (WAIS–IV) subtests, suggesting that cognitive complaints in chronic pain may be attributable to factors other than pain. The current studies examined potential effects of induced pain on Wechsler Memory Scale–Fourth Edition (WMS–IV) visual working memory index (VWM) subtests (Experiment 1, n = 32) and on the immediate portions of WMS–IV auditory memory (IAM) subtests (Experiment 2, n = 55). In both studies, participants were administered one of two subtests (Symbol Span or Spatial Addition for Experiment 1; Logical Memory or Verbal Paired Associates for Experiment 2) normally and were then administered the alternate subtest while experiencing either cold pressor pain induction or a nonpainful control condition. Results indicate that induced pain in nonclinical volunteers did not impair performance on either VWM or IAM performance, suggesting that pain alone does not account for complaints or deficits in these domains in chronic pain patients. Nonpainful variables such as sleep deprivation or emotional disturbance may be responsible for reported cognitive complaints in chronic pain patients.

WAIS-IV Verbal Comprehension Index and Perceptual Reasoning Index Performance is Unaffected by Cold-Pressor Pain Induction

Cognitive complaints are frequently reported by patients with chronic pain, but studies of the effects of pain on different forms of cognition have been inconsistent. In two studies, cold-pressor pain was induced in nonclinical undergraduate volunteers who, under normal conditions, took Verbal Comprehension Index (VCI) subtests (Study 1, n = 57) or Perceptual Reasoning Index (PRI) subtests (Study 2, n = 59) followed by a different VCI or PRI subtest taken during either cold-pressor pain induction or a nonpainful control condition. Pain was not associated with significant reduction in subtest scaled score performance. Results indicate that cold-pressor pain in nonclinical volunteers does not impair Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) VCI or PRI performance and suggest that pain per se should not be expected to substantially influence these cognitive abilities. Viewed together with previous Processing Speed Index and Working Memory Index studies, no cognitive or intellectual functions measured by the WAIS-IV are affected by induced pain. Generalizability of these findings may be limited by the fact that patients with chronic pain may differ in their pain experience from nonclinical volunteers with induced pain.

Effects of Cogmed working memory training on cognitive performance

Research on the cognitive benefits of working memory training programs has produced inconsistent results. Such research has frequently used laboratory-specific training tasks, or dual-task n-back training. The current study used the commercial Cogmed Working Memory (WM) Training program, involving several different training tasks involving visual and auditory input. Healthy college undergraduates were assigned to either the full Cogmed training program of 25, 40-min training sessions; an abbreviated Cogmed program of 25, 20-min training sessions; or a no-contact control group. Pretest and posttest measures included multiple measures of attention, working memory, fluid intelligence, and executive functions. Although improvement was observed for the full training group for a digit span task, no training-related improvement was observed for any of the other measures. Results of the study suggest that WM training does not improve performance on unrelated tasks or enhance other cognitive abilities.