Detecting Cognitive Malingering: State of the Art

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Detecting Cognitive MalingeringState of the Art

• David Stigge-Kaufman
• Forensic Neuropsychology
• July 13, 2006

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Malingering

• Definition
• Intentional production of false or greatly
  exaggerated symptoms for the purpose of attaining
  some identifiable external reward (Iverson
  Binder, 2000)
• Often viewed as pejorative and controversial
• In contrast to making the diagnosis of
  malingering, clinicians seem to be much more
  comfortable diagnosing people with brain damage,
  schizophrenia, alcohol or drug abuse, or
  personality disorders. (p. 831)
• Diagnostic Considerations
• V65.2 (DSM-IV-TR)
• Additional condition that may be a focus of
  clinical attention
• Differential diagnosis
• Factitious Disorder, Somatoform Disorders,
  Depression

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Malingering Checklist

• Presence of a substantial external incentive
• Evidence from neuropsychological testing
• Definite negative response bias (below chance on
  a forced-choice measure of cognitive function)
• Probable response bias on a validity test
• Discrepancies between test data and known
  patterns of brain functioning
• Discrepancies between test data and observed
  behavior
• Discrepancy between test data and reliable
  collateral reports
• Discrepancy between test data and documented
  background history
• Evidence from self-report
• Self-reported history discrepancy with documented
  history
• Self-reported symptom discrepancy with known
  patterns of brain functioning
• Self-reported symptom discrepancy with behavioral
  observations
• Self-reported symptom discrepancy with reports
  from close informants
• Evidence of exaggerated or fabricated
  psychological dysfunction
• Behaviors meeting criteria from groups B and C
  not fully accounted for by psychiatric,
  neurologic, or developmental factors

Slick et al., 1999 Lezak et al., 2004
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Malingered Neurocognitive Dysfunction (MND)

• Definite MND
• Presence of a substantial external incentive
• Definite negative response bias
• Negative response bias cannot be otherwise
  accounted for.

• Probable MND
• Presence of a substantial external incentive
• gt 2 types of N? evidence, or, 1 type of N?
  evidence plus 1 type of evidence from self-report
• Behaviors cannot be otherwise accounted for
• not including negative response bias

Slick et al., 1999
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Clinical Application

• Case Example
• A middle aged electrician had passed out at work
  due to a heat stroke. He was evaluated to
  determine if the residual memory difficulty was
  sufficiently severe to preclude his return to
  work. Across all three delay sets for easy items
  of the Victoria Symptom Validity Test, this man
  had 24/24 recognition. In contrast, he gave only
  three correct responses on the 24 hard items.

Lezak et al., 2004, p. 776
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Clinical Application

• Case Example
• Because 24/24 easy items were correct but only
  3/24 hard items were correct, this did not
  suggest a random response pattern. Normal, above
  chance performance on the easy items demonstrated
  the patients understanding of the instruction
  and that he was not confused about how to
  respond. The below chance performances for the
  three hard conditions have corresponding
  statistical probabilities of .14, .004, and .004.
  Thus, when treated as independent samples, the
  probability of occurrence is .0000022 (.14 X .004
  X .004). This success/failure pattern cannot be
  explained away as due to confusion or
  misunderstood instructions.

Lezak et al., 2004, p. 776
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Effort, Motivation, Response Styles
Frederick et al., 2000
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Researching Malingering

• Case Studies
• Examine test data from individual cases, looking
  for performance levels below chance on
  forced-choice tests.
• Simulation Studies
• May involve comparisons of 4 groups
• 1) Normals faking impairment 3) Normals
  responding honestly
• 2) Patients responding honestly 4) Patients
  faking impairment
• Known-Group Designs
• Establish criterion groups (e.g., patients,
  malingerers), and conduct a systematic analysis
  of similarities and differences between groups
• Differential Prevalence Designs
• Compare groups known to be higher in malingering
  to those who are not

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Sample Malingering Test

• What about the roles of perceived difficulty,
  face validity, or test modality?

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Test Popularity Among Experts

• Forced-choice testing
• Digit Recognition
• Digit Memory Test (DMT)
• Portland Digit Recognition Test (PDRT)
• Victoria Symptom Validity Test (VSVT)
• Computerized Assessment of Response Bias (CARB)
• Word Recognition
• 21-Item Test
• Word Memory Test (WMT)
• Verbal Nonverbal Abilities
• Validity Indicator Profile (VIP)

• Forced-choice testing
• Visual Recognition
• Test of Memory Malingering (TOMM)
• Letter Memory Test
• 48-Pictures Test
• Simplistic tests
• Rey 15-Item Test
• Dot counting Test
• The b Test
• Always/Often Used gt 40
• Always/Often Used 30-39
• Always/Often Used 20-29
• Always/Often Used 10-19

Slick et al., 2004
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Test Sensitivity

• Forced-choice testing
• Digit Recognition
• Digit Memory Test (DMT)
• Portland Digit Recognition Test (PDRT)
• Victoria Symptom Validity Test (VSVT)
• Computerized Assessment of Response Bias (CARB)
• Word Recognition
• 21-Item Test
• Word Memory Test (WMT)
• Verbal Nonverbal Abilities
• Validity Indicator Profile (VIP)

• Forced-choice testing
• Visual Recognition
• Test of Memory Malingering (TOMM)
• Letter Memory Test
• 48-Pictures Test
• Simplistic tests
• Rey 15-Item Test
• Dot counting Test
• The b Test
• Sensitivity gt 85
• Sensitivity 70 84
• Sensitivity 50 69
• Sensitivity lt 49

Sensitivity of malingerers correctly
classified
Lezak et al., 2004, Vickery et al., 2001
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Test Specificity

• Forced-choice testing
• Digit Recognition
• Digit Memory Test (DMT)
• Portland Digit Recognition Test (PDRT)
• Victoria Symptom Validity Test (VSVT)
• Computerized Assessment of Response Bias (CARB)
• Word Recognition
• 21-Item Test
• Word Memory Test (WMT)
• Verbal Nonverbal Abilities
• Validity Indicator Profile (VIP)

• Forced-choice testing
• Visual Recognition
• Test of Memory Malingering (TOMM)
• Letter Memory Test
• 48-Pictures Test
• Simplistic tests
• Rey 15-Item Test
• Dot counting Test
• The b Test
• Specificity gt 85
• Specificity 70 84
• Specificity 50 69
• Specificity lt 49

Specificity of non-malingerers correctly
classified
Lezak et al., 2004, Vickery et al., 2001
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Malingering Patterns in N? Tests

• Pattern Analysis
• WMS-R
• Malingerers Attention/Concentration lt General
  Memory
• Opposite pattern to typical head injury
• WAIS-R Digit Span
• Malingerers Low digit span performance (ss lt 4)
• Reliable Digit Span (sum of longest correct span
  for both trials lt 7)
• Vocabulary Digit Span (low digit span while
  vocabulary is high)
• CVLT
• Malingerers Low recognition (hits
  forced-choice)
• Cutoff scores for recall trials produce variable
  false-positive rates

Iverson Binder, 2000 Larrabee, 2005
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Malingering Patterns in N? Tests

• Pattern Analysis
• Word Memory Test
• Malingerers Inconsistent responding, poor
  initial recognition
• Pattern should reflect severity of impairments
• Category Test
• Malingerers Poor performance on first 2 subtests
• Wisconsin Card Sorting Task
• Malingerers Poor ratios of categories completed
  compared to both perseverative errors and failure
  to maintain set
• Motor Functioning
• Malingerers Suppress motor functioning to
  extreme levels
• Motor decline should only be associated with
  severe brain injury

Iverson Binder, 2000 Larrabee, 2005
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Symptom Exaggeration

• Self-Report of Symptoms
• May be exaggerated due to other variables
  (depression, pain, stress)
• e.g., Post-Concussive Syndrome persisting for
  more than 3 months
• MMPI-2
• Malingerers tend to show elevations in clinical
  scales 1, 2, 3, 7, and 8, the Fake Bad Scale
  (FBS), VRIN, TRIN, the Infrequency-Psychopathology
  Scale F(p).
• The F Scale and F K does not appear to be as
  sensitive, and therefore valid profiles may be
  obtained.
• Caution should be given to interpreting the
  clinical scales and F Scale derivatives, as these
  can be easily influenced by psychiatric
  comorbidities.

Iverson Binder, 2000 Larrabee, 2005
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Summary Conclusions

• Defining Malingering
• External reward, negative response bias, and
  discrepancies in N? data and/or self-report
• Combination of effort and motivation
• Case studies, simulation studies, known-group
  designs, differential prevalence designs
• Detection of Malingering
• Numerous symptom validity tests
• Most forced-choice tests demonstrate excellent
  specificity, but not all show high sensitivity
• Pattern analysis of N? data
• Symptom exaggeration

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References

• Frederick, R.I., Crosby, R.D., Wynkoop, T.F.
  (2000). Performance curve classification on
  invalid responding on the Validity Indicator
  Profile. Archives of Clinical Neuropsychology,
  15, 281-300.
• Iverson, G.L., Binder, L.M. (2000). Detecting
  exaggeration and malingering in
  neuropsychological assessment. Journal of Head
  Trauma and Rehabilitation, 15, 829-858.
• Larrabee, G.J. (2005). Forensic
  Neuropsychology A Scientific Approach. New
  York Oxford University Press.
• Lezak, M.D., Howieson, D.B., Loring, D.W.
  (2004). Neuropsychological Assessment (4th ed.).
  New York Oxford University Press.
• Slick, D.J., Sherman, E.M.S., Iverson, G.L.
  (1999). Diagnostic criteria for malingered
  neurocognitive dysfunction Proposed standards
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• Slick, D.J., Tan, J.E., Strauss, E.H., Hultsch,
  D.F. (2004). Detecting malingering a survey of
  experts practices. Archives of Clinical
  Neuropsychology, 19, 465-473.
• Vickery, C.D., Berry, D.T., Inman, T.H., Harris,
  M.J., Orey, S.A. (2001). Detection of
  inadequate effort on neuropsychological testing
  a meta-analytic review of selected procedures.
  Archives of Clinical Neuropsychology, 16, 45-73.