Forensic Neuropsychology in Personal Injury Cases II

Russell M. Bauer, Ph.D.

July 20, 2006

“Noninjury” Contributors to Neuropsychological Impairment in MHI

      Adversarial patient-examiner relationship Exaggeration or poor effort – – – Impairment as communication Frank malingering for gain; financial incentives Factitious disorders Fatigue, pain, other physical factors Psychiatric disturbance (e.g., psychosis, anxiety, depression) Pre-existing factors affecting neuropsychological performance (e.g., learning disability, limited education) Occupational/life experience factors

Financial Incentives and Disability

 Binder & Rohling (AJP, 1996, 153, 7-10) – Meta-analytic review of financial incentives and symptoms – – – 18 study groups, 2,353 subjects Weighted mean effect size of difference between groups with and without financial incentives was 0.47

More late-onset symptoms in compensation-seeking groups

Checks against False Positives: Consistency Analysis

    Consistency of results between/within domains Consistency with known syndromes – example: “hemi-anomia” Consistency with injury severity Consistency with other aspects of behavior – e.g. memory abilities during vs. apart from formal testing

Post-Concussion Syndrome

Post-Concussion Syndrome: DSM-IV Definition  “acquired impairment in cognitive functioning,

accompanied by specific neurobehavioral symptoms

PTA, etc.) , that occurs as a consequence of closed head injury of sufficient severity to produce a significant cerebral concussion” (LOC,

PCS: DSM-IV Criteria

A B C Hx of head trauma that has caused significant cerebral concussion Evidence from NP testing or quantified cognitive assessment of difficulty in attention or memory Three (or more) of the following occur shortly after trauma and last at least 3 months: – easy fatigue – – – – – – – disordered sleep headache dizziness/vertigo irritability or aggression with little/no provocation anxiety, depression, or affective lability changes in personality apathy or lack of spontaneity

PCS: DSM IV Criteria (cont’d)

D.

E F Symptoms begin after head trauma or else represent a worsening of pre-existing symptoms Significant impairment in social or occupational function; decline from previous functional level Do not meet criteria for dementia and are not better accounted for by another mental disorder

PCS-Like Complaints of NP Dysfunction

     Common Nonspecific Potentially related to non-neurological factors (anxiety, depression, fatigue, stress) Correlate better with distress than with objective indicators of CNS injury Easy to feign or exaggerate

Complaints as “Evidence”

   In the absence of objective neuro-psychological deficit, complaints are often taken to indicate the existence of occult disease There is a difference between

symptoms

(subjective evidence) and

signs

(objective evidence) of illness Symptom reports subject to cognitive distortions and attributional processes

 Complaints (N=45) as “Evidence” “She reports feeling tired, moving slowly, losing her balance, tripping over things, and feeling weak and dizzy. She also reported increased sensitivity to noise, altered perception of the ambient temperature (feeling warm when others are comfortable), poor concentration, forgetfulness, finding once routine activities now complicated, diminished sexual functioning, sleep problems, fatigue and low energy level, anxiety and nervousness, “panic attacks”, lack of patience, decline in handling household chores, fear of certain situations, decline in recreational activities, concerns and worried about her health, depressed mood, decline in her ability to work, diminished interest in pleasurable activities, weight gain of 55 pounds, feelings of worthlessness and guilt, difficulty with language and word-finding, difficulty with concentration and thought processing, difficulties with making conversation and understanding it, writing slowly and illegibly, finding it difficulty to get started on things, trouble making decisions, difficulty pronouncing words, forgetting people’s names, getting her mind off certain thoughts, misplacing things, and becoming easily distracted. Scattered and confused behavior permeates all aspects of her life. She also reports periods of time where she becomes completely disoriented to her place and purpose. She experiences severe headaches, shoulder, neck, back, and leg problems, severe depression and cognitive dysfunction”.

Problems with Using Complaints as Evidence of MHI

 Mittenberg et al. (1992, 1997): “expectation as etiology” – ‘imaginary concussion’ produces symptom complaint cluster identical to that reported by patients with ‘real’ head injury – patients with minor TBI significantly underestimate degree of pre-injury problems

Major PCS Symptoms “Imaginary concussion” produces a pattern of symptom reports virtually identical to that seen after MHI

MHT patients significantly underestimate preinjury symptoms compared to a noninjured control group

Base Rates of Post-Concussion Symptoms ( Larrabee ,

Symptoms Headaches Fatigue Dizziness Blurred Vision Bothered by Noise b Bothered by Light Insomnia b Poor Concentration Irritability Loss of Temper Memory Problems b Anxiety Medical Controls 62% 58% 26% 22% 18% c 52% d 26% 38% 20% 54% Non-CNS Litigants 88% 79% 44% 32% 29% c 92% d 78% 77% 53% 93% a

a Non CNS Litigants: in litigation for emotional or industrual stress, but not for CNS injuries, b significant difference from controls at 1m, but not 1y in Dikmen et al., 1986; c ”hearing problems in Lees-Haley & Brown, 1993; d ”sleeping problems in Lees Haley & Brown, 1993

Conclusions

   You don’t have to have had a head injury to have post-concussion symptoms Once something bad has happened to you, you tend to attribute more of your problems to it Complaints reflect the subjective, not necessarily the objective, consequences of MTBI

Implications for Understanding PCS

       5% of MHI patients have persistent deficits Physiogenic causes likely operative in the first 1-3 months Psychogenic causes important thereafter Complaints have low specificity for MHI Baserate issues important Attributional processes important Suggests need for a scientific approach to assessing persistent complaints after MHT

Assessment of Malingering and Poor Effort

   Issues 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

Effort, Motivation, & Response Styles

Frederick et al., 2000

Slick (1999)

 Considers evidence from NP and self report  NP criteria – – Definite or probable response bias Discrepancies/inconsistencies between NP data and patterns of brain functioning, collateral reports, reports of past functioning

Slick et al, 1999 (cont’d)

    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

Malingering Research Literature

    Case study Simulation studies – Interpretive issues – Appropriate designs Differential prevalence design – contrasting high and low baserate groups Known-groups design – Selecting groups on the basis of malingering criteria (e.g., Slick, et al)

Selecting Specialized Cognitive Effort Tests

 Ease of use  Credibility of rationale  Operating Characteristics – Incremental validity – TBI vs. PPCS  Coaching issues  Not likely to be a “best” test

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

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

  Neuropsychology for Physicists: “Neuropsychological testing was highly consistent with her 2/8/97 automobile accident. That is, she showed evidence suggestive of significant shearing damage, the frontal system being damaged bilaterally, with relative sparing of the intentional memory system structures and posterior brain areas, a pattern expected with an injury in which the brain is spun and then violently counterspun within the skull. She also showed significant deficits with passive attention plus more problems with incidental than intentional memory. This suggests reticular activating system damage such as would occur with significant shearing and/or when the brain is slammed down against the tentorium. Hypothalamic symptoms were numerous. Damage to this nucleus is quite common in this type of injury as well. Finally, Ms. X showed some right posterior deficits, but sparing of left posterior function. This suggests a possible right posterior/left frontal coup/contracoup pattern overlaying the bilateral frontal system shearing. This dual pattern can occur in an accident such as hers where the driver is seat-belt restrained and the left front of her car is hit. Ms. X reported symptoms consistent with mild to moderate depression. The pattern of her neuropsychological deficits was inconsistent with scores of non-head-injured patients suffering from depression. The pattern of Ms. X’s neuropsychological damage and residual strengths, the nature of her 2/8/97 MVA, and the timing of symptom onset all indicate the cause of her present brain damage to be the 2/8/97 accident.

Common “suspect” neuropsychological signs on NP testing

      Recognition << 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 – Hemi-anomia

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 neuropsychological differences

Lees-Haley 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

Lees-

Haley FBS (cont’d)

    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 20’s, with varying false positive rates; increasing security with scores > 25-27

Patient after MVA, with no LOC, undergoes neuropsychological testing, has a normal neuropsychological evaluation. He has a VIQ of 106 and a PIQ of 89. On WMS, he has an MQ of 108, but only remembers an average of 6 items on Logical Memory. Other verbal memory tests are normal. The patient is mildly depressed and faces several orthopedic surgeries for lower extremity injuries. The neuropsych is summarized:

“

Based on the present test results there is evidence that Mr. X is experiencing significant cortical dysfunctioning. His organic deficits appear to be highly lateralized and focal in nature. Specifically, he is manifesting significantly impaired visual motor skills relative to verbal skills. This finding is consistent with Organic Brain Dysfunction and in particular consistent with Nondominant Hemisphere Dysfunction.

In addition, when one compares Mr. X’s premorbid level of intellectual functioning to his present level of intellectual functioning it is clear that his overall intelligence has declined (no records obtained by him, attentional problems/poor school attendance later discovered from records I obtained). In addition, test results indicate localized organic impairment for both short term verbal memory functioning as well as delayed verbal memory functioning. This finding is highly consistent with dominant temporal cortex lesioning. With regard to psychological functioning, there is evidence of clinically significant levels of depression (MMPI 2-scale at 68, no other scales elevated, patient reports loss of interest and mild dysphoria). It is strongly believed that the patient’s organic dysfunctioning and depression are directly related to the automobile accident on February 8, 1997.”