Feigning Issues in Brain Injury

CHAPTER 17

DAVID T. R. BERRY

BRITTANY D. WALLS

CHELSEA M. BOUQUET

ELIZABETH R. WALLACE

OVERVIEW

“Malingering” is defined by the Diagnostic and Statistical Manual of Mental Disorders (fifth edition; DSM-5; American Psychiatric Association [APA], 2013) as “. . . the intentional production of false or grossly exaggerated physical or psychological symptoms, motivated by external incentives such as avoiding military duty, avoiding work, obtaining financial compensation, evading criminal prosecution, or obtaining drugs” (p. 726). Malingering must be distinguished from factitious disorder (see section Diagnostic Considerations) and conversion disorder (functional neurological symptom disorder; see section Diagnostic Considerations). This diagnostic framework has been carried over virtually unchanged since DSM-III (APA, 1980) and has been criticized for requiring extremely challenging distinctions, such as discriminating voluntary versus involuntary control and internal versus external motivations (Berry & Nelson, 2010). Nevertheless, the DSM-5 malingering framework is enshrined in the current psychiatric nosology and thus cannot be ignored.

As discussed in previous chapters, mild traumatic brain injury (mTBI) is the most common form of traumatic brain injury (TBI), representing approximately 80% of TBIs (Kraus & Chu, 2005). Because by definition, mTBI involves only a brief loss or alteration of consciousness and no findings of pathology on neuroimaging of the brain, patients with this diagnosis have limited means to document their injury in litigation or disability proceedings. This may be at least a partial cause of reports that a significant proportion of mTBIs undergoing neuropsychological evaluation in compensation-seeking circumstances have been found to have evidence of poor effort and cooperation using objective procedures. As reviewed in the following sections, approximately 40% of compensation-seeking mTBI cases are thought to feign during neuropsychological evaluations. These findings suggest that complaints of long-term cognitive and behavioral deficits in a compensation-seeking mTBI patient should have careful and formal consideration given to the possibility of feigned symptoms.

HISTORY

Vickery, Berry, Inman, Harris, and Orey (2001) meta-analytically reviewed published studies on the detection of feigned deficits during neuropsychological testing. They characterized the extant literature to that date as having undergone three major phases. Initially, the forensic neuropsychology community was resistant to the notion that clients could convincingly feign deficits on testing. However, influential papers by Faust, Hart, and Guilmette (1988) and Heaton, Smith, Lehman, and Vogt (1978) conclusively demonstrated that relatively naive individuals instructed to fake neuropsychological deficits could successfully do so and escape detection by clinical judgment. In the subsequent second phase, several procedures introduced by Rey (1964) and popularized by Lezak (1983) began to be used by many neuropsychologists.

In the third phase, the symptom validity paradigm (more recently, widely known as Performance Validity Tests or PVTs) described by Binder (1990) and Hiscock and Hiscock (1989) began to gain wide acceptance by neuropsychologists. In the most popular format, a patient who is claiming memory deficits is given a series of trials, as shown in Figures 17.1 and 17.2, in which he or she is first shown a simple stimulus (5-digit number) to remember, followed by a blank delay, and then asked to choose between two alternative 5-digit numbers, one of which was given to remember. Because of the dichotomous choice involved, the binomial theorem may be used to calculate the probability of making a given number of correct choices in the face of no retained ability (random guessing). If a test-taker scored statistically significantly below chance, this was taken as clear evidence of suppressed ability, because in order to perform this poorly, the correct answer must have been recognized.

Figure 17.1. Digit memory test stimulus card.

Figure 17.2. Digit memory test answer card.

Subsequently, it was determined that instructed or simulating malingerers rarely performed this poorly. Thus, the threshold was later revised to compare a test-taker’s performance to a “normative group” of non–compensation-seeking patients with a severe level of the same pathology. The “normative group” performance was used to determine a cutting score, usually set to correctly identify 90% of the normative group, to identify feigned deficits. Vickery et al. (2001) reported that the latter approach resulted in an overall specificity rate of 0.957 (percentage of honest test-takers correctly classified) and a sensitivity rate of 0.560 (percentage of malingering test-takers correctly classified). These authors concluded that such procedures should be used in all evaluations of compensation-seeking neuropsychological evaluees. These findings were updated and substantially replicated a decade later in a follow-up meta-analysis by Sollman and Berry (2011).

Results from these meta-analyses as well as numerous independent supportive studies led professional organizations to recommend the use of symptom validity tests in all neuropsychological evaluations, particularly those in a compensation-seeking context. For example, the National Academy of Neuropsychology published a position paper that stated, “. . . the assessment of symptom validity is an essential part of a neuropsychological evaluation (and) the clinician should be prepared to justify a decision not to assess symptom validity as part of a neuropsychological evaluation” (Bush et al., 2005, p. 421).

PATHOPHYSIOLOGY/ETIOLOGY

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