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Malingering

Malingering. To enact or exaggerate disability Conscious simulation Expression highly variable No definitive means of detection. Many reasons for poor test performance Once detected evidence of cognitive abnormality need to determine basis of those deficits

vladimir-reyes
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Malingering

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  1. Malingering • To enact or exaggerate disability • Conscious simulation • Expression highly variable • No definitive means of detection

  2. Many reasons for poor test performance • Once detected evidence of cognitive abnormality need to determine basis of those deficits • Neurological syndrome under investigation • Enactment/exaggeration • Other neuropsychological risk factors

  3. No definitive means of detection However, there are scientific means to expose attempts to exaggerate cognitive impairments and to provide objective evidence of deliberate attempts to achieve poorly.

  4. Tests most often employed • 15-Item Visual Memory Test • Digit Repetition • Test of Memory Malingering • Word Memory Test • Recognition Memory Test • ACS Effort Measures: LM, VPA, VR, RDS, Des • MMPI-II

  5. 15-Item Visual Memory Test A B C 1 2 3 a b c O □  I II III

  6. 15-Item Visual Memory Test • Lezak: Anyone who is not significantly deteriorated can recall at least three of the five character sets • Frequently used cut-off = 9/15

  7. A B C D 1 2 3 4 I II III IIII

  8. A B S 1 2 3

  9. A P O Τ

  10. A P D I C O I O 1

  11. 15-Item Visual Memory Test • Good specificity • Poor sensitivity

  12. Digit Repetition • Contrasts between (WMS-IV) Memory and Visual Working Memory • Contrasts between (WAIS) VC and Working Memory

  13. Reliable Digit Span • Sum of the longest string of digits recalled on both trials of each digit length for both forward and backward condition. • Score of 7 or less suggestive of malingering/exaggeration

  14. Supraspan Learning • Sensitivity, specificity data not available • Simple task with face validity

  15. Stimulus: 9, 1, 8, 4, 2, 7 Response • 5, 8, 4, 7 • 9, 1, 8, 4, 7 • 9, 1, 8, 7 • 9, 8, 4, 7 • 9, 1, 8, 4, 2, 7 (correct) • 9, 1, 4, 2, 7 • 9, 1, 2, 7 no 4, 7 • 9, 1, 4, 8, 2, 7 • 9, 1, 4, 2, 8, 7 • 9, 1, 8, 4, 2, 7 (correct) • 9, 1, 4, 2, 8, 7

  16. Case example 2 • Digit Span 3 items forward unreliably 3 items backwards unreliably

  17. Stimulus 7, 5, 8, 3, 6 • Response • 7, 5, 8, 6 • 5, 8, 3, 7 • 7, 5, 6, 3 • 7, 8, 5, 6 • 7, 5, 3, 8, 6 • 8, 5, 7, 6 • 7, 8, 3, 5, 6 • 8, 7, 5, 6 • 7, 8, 5, 6, 3 • 8, 7, 5, 3, 6

  18. Not only were her answers highly improbable, but her first attempt at the task confirmed that she could hold at least three numbers in mind (which her extremely poor performance on the Digits Forward section of the WAIS-III Digit Span subtest would suggest that she could not). Considered in conjunction, her results on the tests detailed above provided clear evidence of a deliberate attempt to exaggerate cognitive impairment.

  19. NB: frequently asked whether reference to fatigue, headache, pain, depression etc etc (or some combination of these factors) could explain the poor performances.

  20. Test of Memory Malingering • 50 items, two trials • Recognition memory – forced choice • Score of below 45/50 suggestive of malingering • Research has demonstrated that performance on the test is unaffected by affective status (Rees, Tombaugh and Boulay, 2001; Ashendorf et al 2004)

  21. Some work done with children suggesting that from a young age (6 years) it is appropriate. • Good specificity • ? Sensitivity

  22. Word Memory Test • 50 words presented to the patient in pairs

  23. DOG CAT

  24. COMPUTER TERMINAL

  25. MILK COFFEE

  26. Recognition Memory Testing – forced choice Eg DOG RABBIT

  27. High Sensitivity ???Specificity Merten, Bossink and Schmand, JCEN, 2007 Highlight the fact that the WMT may not be appropriate for severely impaired patients.

  28. Inconsistencies • Bizarre or unusual performance • Performance levels below the usual range for persons who have complained of symptoms or disorder on an organic basis • Failure on all tasks (irregardless of function or level of difficulty)

  29. Malingering does not exclude the possibility of brain damage • Feigning of an illness may be symptomatic of that illness • Malingering does preclude accurate assessment of the nature and degree of ‘real’ disability

  30. Question of enactment or exaggeration most often arises in the context of a medico-legal assessment – clear incentive to perform poorly However, any clinician must always be aware that exaggeration may occur.

  31. In this context that one must be acutely aware of the expected outcome following any neurological insult. Eg Severity of TBI and expectations of nature and magnitude of any residual deficits Course of deficits over time.

  32. CASE: M.V. • 33 y.o female • Education; Year 11 • 19/11/04: assaulted during the course of her work (manager of a TAB agency for 5 years) • Taken to a local medical centre, examined and sent home • 12/12/04: Consulted her local doctor complaining of headaches, paraesthesia of the right thigh, memory loss and an inability to count and spell • Angiography: Marked diffuse narrowing of the L ICA ( a result of carotid dissection)

  33. Ax: 9/10/05 • WAIS-R - Why

  34. WAIS-IV

  35. Arithmetic • Unable to answer even items 1 and 2 Digit Span • 3 Forwards unreliably • 3 backwards reliably Coding - Reversed most (but not all) items

  36. WMS-IV Auditory Memory = 74 Visual Memory = 60 Visual Working Memory = 50 Immediate Memory = 67 Delayed Memory = 58

  37. 15-Item Visual Memory Test Trial 1 = 4/15 Trial 2 = 4/15

  38. RMT Faces = 16/50* *Below chance – meaning??

  39. Case: JH 43 yo male TBI: 21/6/04 struck as a pedestrian while crossing road Claimed to remember stepping onto main road. Having to cross in front of three lanes of traffic. Passing in front of two lanes and then “bang” as was hit In hospital for two to three days

  40. ???? Length of PTA *Single best measure of TBI severity Often difficult to determine in malingering population • ? Validity of any report • Often claim that memory still has not returned

  41. Chief subjective complaint was of a dense retrograde amnesia • Could remember his parents • No recollection of primary, secondary or tertiary studies. Reported that he “probably” completed a degree in law and “maybe” a masters degree in that subject • Reports indicated that he came to Australia in 1996. No recollection of having done so • No recollection of establishing or operating the bakery that he did while in this country.

  42. WAIS-IV Matrix Reasoning 4 Visual Puzzles 4 Block Design 5 Digit Symbol 2

  43. WMS-IV Visual Memory 71 Visual Working Mem. 50

  44. Supraspan Learning 6, 1, 7, 4, 8, 2 20 trials – still unable to repeat correctly over two consecutive trials

  45. 15-Item Visual Memory Test No rows correctly reproduced (see below) Recognition Memory Test Faces 26/50

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