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Forensic Neuropsychology in Personal Injury Cases II

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Title: Compensation for Mental Injury Subject: Forensic Neuropsychology Course Author: Russell M. Bauer Last modified by: rbauer Created Date: 7/15/1997 9:29:38 PM – PowerPoint PPT presentation

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Title: Forensic Neuropsychology in Personal Injury Cases II


1
Forensic Neuropsychology in Personal Injury Cases
II
  • Russell M. Bauer, Ph.D.
  • July 17, 2008

2
Summary from Last Week
  • Persistent deficits after mTBI are rare
  • Even when present, severity of deficits is small
    (lt.5 SD)
  • NP impairment is often the only objective
    indicator of abnormality
  • What to make of this?
  • IMPORTANT REMINDER SOME PATIENTS DO SUFFER
    RESIDUAL DEFICITS!!

3
Noninjury Contributors to Neuropsychological
Impairment in MHI
  • Adversarial patient-examiner relationship
  • Expectation/attributional processes
  • Diagnosis threat, role stereotypes
  • Exaggeration or poor effort
  • Impairment as communication
  • Frank malingering for gain financial incentives
  • Factitious disorders
  • Fatigue, pain, other physical factors
  • Psychiatric/behavioral disturbance (e.g.,
    psychosis, anxiety, depression)
  • Cogniform disorder/cogniform condition
  • Pre-existing factors affecting neuropsychological
    performance (e.g., learning disability, limited
    education)
  • Occupational/life experience factors

4
Assessment of Malingering and Poor Effort
  • Issues/problems with definition
  • Intentional (intention)
  • Fabrication or exaggeration (action)
  • For purposes of gain (motive)
  • Explanatory models (Rogers, 1997)
  • Pathological (mental disorder)
  • Criminological (fake)
  • Adaptational (meeting adversarial demands)
  • Cognitive vs. Somatic Malingering

5
Diagnosis Threat (Suhr Gunstad, 2002)
  • 37 MHI (17 in diagnosis threat condition)
  • Diagnosis threat told selected because of a MHI
    history a growing number of studies show that
    many individuals with head injury show cognitive
    deficits in neuropsychological tests

6
Suhr Gunstad, 2002
7

Suhr Gunstad, 2002
8
Cogniform Disorder/Cogniform Condition
  • Patients with excessive cognitive complaints
  • Difficulties with existing diagnostic options
  • Symptom specificity
  • Intentionality
  • Presence of external incentive

9
  • COGNIFORM PRESENTATION

10
Pain and NP Performance
  • Pain itself associated with mild NP performance
    decrements
  • Pain medications
  • Opioids attention/concentration (on dose
    escalations)
  • Neurobiological systems
  • ACC, NA, extended amygdala
  • Pain ALONE would not explain a -2SD discrepancy
    in severity

Block Cianfrini Neurorehabilitation, 2013
Moriarty, et al Prog Neurobiol, 2011.
11
Depression and NP
  • Moderate effect sizes in executive function,
    memory and attention (-.34 to -.65)
  • After treatment/remission,
  • Executive/attention -.52 to -.61 in patients
    with depression relative to controls (sig)
  • Memory -.22 to -.54 (nonsig)
  • Suggests that poor cognition is a central, core
    feature

Rock, et al., Psychological Medicine, 2013
12
Lim et al, Int Psychogeriatr, 2013
  • Meta-analysis of a total of 22 trials involving
    955 MDD patients and 7,664 healthy participants.
    MDD lt healthy
  • Digit Span, CPT (attention)
  • TMT-A, Digit Symbol (processing speed)
  • Stroop, WCST, Verbal Fluency (exec)
  • Immed verbal memory (memory)MDD
  • Other tests did not differentiate

13
Larrabee Rohling, 2013
14
Effort, Motivation, Response Styles
Frederick et al., 2000
15
Malingering Algorithms Slick (1999)
  • Considers evidence from NP and self report
  • 4 criteria
  • Presence of incentive
  • Evidence from NP
  • Evidence from self-report
  • Not better accounted for by.

16
Slick et al. (1999 contd)
  • NP criteria
  • Definite (below chance) or probable (low)
    response bias on FC measures
  • Discrepancies/inconsistencies between
  • NP data and patterns of brain functioning
  • NP data and observed behavior
  • NP data and reliable collateral reports
  • NP data and past history

17
Slick et al. (1999 contd)
  • Self-report criteria
  • Self-report discrepant with history
  • Self-report discrepant with known patterns of
    brain functioniong
  • Self-report discrepant with behavioral
    observations
  • Self-report discrepant with collateral
    information
  • Evidence of exaggerated or fabricated
    psychological dysfunction

18
Slick et al, 1999 (contd)
  • DEFINITE MND
  • Presence of financial incentive
  • Definite negative response bias
  • Behaviors that meet criteria for negative
    response bias that are not fully accounted for by
    psychiatric, neurological, or developmental
    factors
  • PROBABLE MND
  • Presence of financial incentive
  • Two or more types of evidence from NP, excluding
    definite response bias, or one piece of evidence
    from NP and one from self-report

19
Malingering Research Literature
  • Case study
  • Simulation studies
  • Interpretive issues
  • Appropriate designs
  • Differential prevalence design
  • contrasting high and low baserate groups (e.g.,
    groups with and without financial incentives)
  • Valuable mostly for determining average
    performances
  • Known-groups design
  • Selecting groups on the basis of malingering
    criteria (e.g., Slick, et al)
  • Examining differences between the groups

20
Selecting Specialized Cognitive Effort Tests
  • Ease of use
  • Credibility of rationale
  • Operating Characteristics
  • Incremental validity
  • TBI vs. PPCS
  • Coaching issues
  • There is not likely to be a best test in all
    circumstances

21
Commonly Used Specialized Tests
  • Portland Digit Recognition
  • Digit Memory Test
  • Computerized Assessment of Response Bias (CARB)
  • Word Memory Test (WMT)
  • Victoria Symptom Validity Test
  • Test of Memory Malingering
  • Validity Indicator Profile
  • Rey 15-Item Test
  • Dot Counting Test

22
Detecting Anomalous Results with Embedded
Measures and Performance Patterns
  • Measures within standard NP tests that signify
    noncredible or suspect performance
  • Identification of such measures can be rational
    or empirical
  • May be less subject to coaching than separate
    measures

23
Pattern Analysis
  • Pattern Analysis
  • With HRNB, DFA outperforms clinicians (80-90 v.
    50-60)
  • Most DFAs multivariate , consisting of attention
    and memory measures
  • Generally, malingers score better on hard
    measures
  • DFAs exist for WMS-R, WMS-III, WAIS-R, WAIS-III
    and other tests
  • Before using, investigate whether the DFA was
    validated/cross validated with known groups or
    simulators

Iverson Binder, 2000 Larrabee, 2005
24
Common suspect neuropsychological signs on NP
testing
  • Recognition ltlt recall (hits, discriminability)
  • Extremely poor DS in the context of normal
    auditory comprehension (RDS)
  • Motor slowing (e.g., reduced tapping) relative to
    overt motor disability
  • Excessive failures-to-maintain-set on WCST
  • Discrepancies between test level and level during
    informal interaction
  • Other impossible signs

25
Embedded Measures Motor, Sensory, and
Perceptual-Motor
  • Perceptual-motor pseudoabnormality should not be
    overlooked b/c of emphasis on higher cognitive
    disabilities
  • Approaches
  • Neurologic exam
  • Sensorimotor impairments on NP exam
  • Findings
  • RCFT copy 50 sensitive with lots of FP
  • Malingering groups favor memory over
    visuoconstructive impairment (e.g. memory trials
    of RCFT discriminate better)
  • Generally large grip strength effect size in K-G
    designs
  • Reduced FT speed in the context of MHI

26
Embedded Cognitive Measures
  • WMS-R/WMS-III
  • Malingerers Attention/Concentration lt General
    Memory
  • Opposite pattern is more typical of head injury
  • Rarely-missed index on LM delayed recognition
    trials
  • WAIS-R/WAIS-III Digit Span
  • Malingerers Low digit span performance (ACSS lt
    5)
  • Reliable Digit Span (sum of longest correct span
    for both trials lt 8)
  • 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
  • Variable results with most widely used cutoffs
    (Millis et al) Total lt 35, LDCR lt7, delayed
    recognition lt11, discriminability lt 81
    sensitivity in question, not specificity

27
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

Iverson Binder, 2000 Larrabee, 2005
28
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29
Why being a knowledgeable neuropsychologist is
important
  • You know likely patterns of impairment
  • You know psychometric relationships among tests
  • You know course of recovery
  • You know about contributory factors (e.g., LD,
    depression, etc.)
  • You can compare what you see to what you expect

30
Some Take Home Messages
  • Use multiple measures (forced choice, embedded,
    etc.)
  • Clarify your goals sensitivity, specificity,
    etc.
  • Be aware of correlations among malingering
    measures
  • Look for emerging research on sensitivity/specific
    ity of multiple indicators

31
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
32
Detecting Somatic Malingering
  • Symptom report, as well as cognitive performance,
    can be controlled by the litigant
  • Use of MMPI-2
  • F-scale, F(p)
  • VRIN, TRIN
  • Subtle-Obvious
  • F-K index
  • Revised Dissimulation Scales
  • These scales may not be sufficiently sensitive to
    TBI-related claims, despite neuro-psychological
    differences

33
MMPI Measures
  • FBS 43 items honest with bad injury
    Originally the Fake Bad Scale and now the
    Symptom Validity Scale (FBS)
  • Response Bias Scale (RBS) 28 items that
    predicted failure on CARB and WMT
  • Henry-Heilbronner Index (HHI) 15 items
    sensitive to neurocognitive complaints in the
    months following head trauma

34
FBS
  • Model of goal-directed behavior
  • Want to appear honest
  • Want to appear psychologically normal except for
    the influence of injury
  • Avoid admitting longstanding problems
  • Minimize pre-existing complaints
  • Minimizing pre-injury antisocial or illegal
    behavior
  • Presenting plausible injury severity

35
Lees-Haley FBS (contd)
  • 18 True , 25 False
  • Does not correlate very strongly with F-scale
    derivatives
  • Most scale items overlap with neurotic side of
    MMPI
  • Cut-off mid 20s, with varying false positive
    rates increasing security with scores gt 25-27

36
FBS Operating Characteristics
  • Most frequently failed indicator of MND
    (Larrabee)
  • FBS gt 27 has Sn.46 , Sp.96, better than F or Fb
    (Greve et al)
  • Sensitive to symptom exaggeration in personal
    injury, not just litigation
  • Cutoffs determine TP, FP rate

37
Critical Studies
  • Butcher et al (2003)
  • Unacceptably high FP of FBS (24 of males, 37.9
    of females exceeded cutoffs)
  • Psychiatric, corrections, medical, pain, VA,
    personal injury litigants
  • No measures of symptom validity external to the
    MMPI
  • No report of who was litigating
  • Cant compute specificity or sensitivity without
    this information
  • Bury Bagby (2002)
  • PTSD vs. students (standard and exaggeration
    instructions)
  • F family produced best overall classification
    rates
  • Entire PTSD sample were being evaluated for
    workplace disability
  • Mean PTSD FBS was 26.31
  • No independent measures of malingering or
    exaggeration

38
RBS
  • Sensitivity low (.34), specificity high (.96-.98)
  • Specifically designed to predict SVT failure
  • Outperforms F-family and FBS in doing this
  • Seems to measure more cognitive than somatic
    factors

39
HHI
  • Neurocognitive complaints in the immediate
    postinjury period.
  • 9 items overlap with FBS, 4 with original
    Pseudoneurologic Scale PNS)
  • Sensitivity 80, Specificity 89 with a cutoff of
    gt 8

40
Classification Accuracy of FBS, RBS, and HHI
Dionysus et al., Arch Clin Neuropsychol, 2011
41
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42
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