Forensic Neuropsychology in Personal Injury Cases II Russell M. Bauer, Ph.D. July 20, 2006

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

Financial Incentives and Disability v 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 v Consistency of results between/within domains v Consistency with known syndromes –example: “hemi-anomia” v Consistency with injury severity v 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 v “acquired impairment in cognitive functioning, accompanied by specific neurobehavioral symptoms, that occurs as a consequence of closed head injury of sufficient severity to produce a significant cerebral concussion” (LOC, PTA, etc.)

PCS: DSM-IV Criteria A Hx of head trauma that has caused significant cerebral concussion B Evidence from NP testing or quantified cognitive assessment of difficulty in attention or memory C 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. Symptoms begin after head trauma or else represent a worsening of pre-existing symptoms E Significant impairment in social or occupational function; decline from previous functional level F Do not meet criteria for dementia and are not better accounted for by another mental disorder

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

Complaints as “Evidence” v In the absence of objective neuro-psychological deficit, complaints are often taken to indicate the existence of occult disease v There is a difference between symptoms (subjective evidence) and signs (objective evidence) of illness v Symptom reports subject to cognitive distortions and attributional processes

Problems with Using Complaints as Evidence of MHI v 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

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

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

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

Frederick et al., 2000 Effort, Motivation, & Response Styles

Slick (1999) v Considers evidence from NP and self report v 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) v DEFINITE MND v Presence of financial incentive v Definite negative response bias v Behaviors that meet criteria for negative response bias that are not fully accounted for by psychiatric, neurological, or developmental factors v PROBABLE MND v Presence of financial incentive v 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 v Case study v Simulation studies –Interpretive issues –Appropriate designs v Differential prevalence design –contrasting high and low baserate groups v Known-groups design –Selecting groups on the basis of malingering criteria (e.g., Slick, et al)

Selecting Specialized Cognitive Effort Tests v Ease of use v Credibility of rationale v Operating Characteristics –Incremental validity –TBI vs. PPCS v Coaching issues v Not likely to be a “best” test

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

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

Common “suspect” neuropsychological signs on NP testing v Recognition << recall (hits, discriminability) v Extremely poor DS in the context of normal auditory comprehension (RDS) v Motor slowing (e.g., reduced tapping) relative to overt motor disability v Excessive failures-to-maintain-set on WCST v Discrepancies between test level and level during informal interaction v Other “impossible” signs –Hemi-anomia

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

Lees-Haley FBS v 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) v 18 “True”, 25 “False” v Does not correlate very strongly with F- scale derivatives v Most scale items overlap with “neurotic” side of MMPI v Cut-off mid 20’s, with varying false positive rates; increasing security with scores > 25-27