Title: Forensic Neuropsychology in Personal Injury Cases II
1Forensic Neuropsychology in Personal Injury Cases
II
- Russell M. Bauer, Ph.D.
- July 17, 2008
2Summary 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!!
3Noninjury 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
4Assessment 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
5Diagnosis 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
6Suhr Gunstad, 2002
7Suhr Gunstad, 2002
8Cogniform Disorder/Cogniform Condition
- Patients with excessive cognitive complaints
- Difficulties with existing diagnostic options
- Symptom specificity
- Intentionality
- Presence of external incentive
9 10Pain 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.
11Depression 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
12Lim 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
13Larrabee Rohling, 2013
14Effort, Motivation, Response Styles
Frederick et al., 2000
15Malingering AlgorithmsSlick (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.
16Slick 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
17Slick 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
18Slick 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
19Malingering 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
20Selecting 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
21Commonly 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
22Detecting 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
23Pattern 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
24Common 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
25Embedded 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
26Embedded 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
27Malingering 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(No Transcript)
29Why 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
30Some 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
31Symptom 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
32Detecting 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
33MMPI 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
34FBS
- 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
35Lees-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
36FBS 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
37Critical 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
38RBS
- 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
39HHI
- 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
40Classification Accuracy of FBS, RBS, and HHI
Dionysus et al., Arch Clin Neuropsychol, 2011
41(No Transcript)
42(No Transcript)