Methods to detect malingering in amnesia: a review

Abstract

Clinicians sometimes encounter patients they suspect are feigning their symptoms of amnesia, usually in order to achieve financial gain or to avoid criminal punishment. We review current methods available for detecting malingering in cases of amnesia. Certain neuroscientific methods, such as fMRI and pupil dilation measures, show promise in detecting malingering, especially because it is difficult for patients to trick the machines – though the tests require special equipment to employ. Multiple tests are available to assess whether a patient is feigning symptoms of anterograde amnesia; any test involving the storage and retrieval of new information is potentially useful. A pattern can be observed whereby simulators tend to exaggerate their symptoms, scoring below chance performance and/or below the baseline of patients with genuine amnesia. Detecting malingering in retrograde amnesia can be more challenging as the information in question concerns the past and can be beyond the experimenter’s control. Therefore, the selection of methods available is more limited, but the general pattern appears to be that simulators perform worse than the baseline set by organic amnesiacs. The review suggests that there is no method that can detect malingering beyond any absolute doubt, but if a patient consistently scores below chance or below the baseline of genuine amnesiacs on multiple different tests - and their underperformance cannot be explained by other plausible mechanisms - then there is reason to suspect malingering.

Full text

Clinicians sometimes encounter patients they suspect are feigning their symptoms of amnesia, usually in order to achieve financial gain or to
avoid criminal punishment. We review current methods available for detecting malingering in cases of amnesia. Certain neuroscientific
methods, such as fMRI and pupil dilation measures, show promise in detecting malingering, especially because it is difficult for patients to
trick the machines –though the tests require special equipment to employ. Multiple tests are available to assess whether a patient is feigning
symptoms of anterograde amnesia; any test involving the storage and retrieval of new information is potentially useful. A pattern can be
observed whereby simulators tend to exaggerate their symptoms, scoring below chance performance and/or below the baseline of patients
with genuine amnesia. Detecting malingering in retrograde amnesia can be more challenging as the information in question concerns the
past and can be beyond the experimenter’s control. Therefore, the selection of methods available is more limited, but the general pattern
appears to be that simulators perform worse than the baseline set by organic amnesiacs. The review suggests that there is no method that
can detect malingering beyond any absolute doubt, but if a patient consistently scores below chance or below the baseline of genuine
amnesiacs on multiple different tests - and their underperformance cannot be explained by other plausible mechanisms - then there is reason
to suspect malingering.
Espen A. Sjoberg1,2, Riccardo Russo1, & Keith Jenkins3
Malingerers of amnesia generally fall into
two motivational categories:
1) Financial gain
In cases of injury, patients may feign
amnesia or reduced cognitive deficits in
order to substantiate an insurance claim.
Thus, feigning amnesia in this case is
motivated by the possibility of external
gains (Binder & Rohling, 1996).
2) Avoiding criminal punishment
Accused criminals may feign amnesia in
order to absolve any responsibility for their
crimes, thus avoiding or reducing prison
sentences (Pyszora et al., 2003).
When amnesia is reported, it falls into two
categories: retrograde amnesia is the
inability to recall events prior to the onset of
the condition, while anterograde amnesia
is the inability to learn new knowledge.
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Methods to detect malingering in
amnesia: a review
1University of Essex, 2Oslo and Akershus University College, 3St. Andrew’s Healthcare
The key variable to detecting malingering is
effort, specifically motivated effort
(intention). Those who simulate amnesia will
put extra effort into deliberately giving a
poor performance.
In tests that involve chance, such as
Symptom Validity Tests (SVTs), malingerers
perform worse than genuine amnesiacs.
This occurs because they actively try to
remember the correct answer, in order to
report the incorrect one. This is also known
as negative response bias (Slick et al.,
1999). If participants are told that the test is
getting harder (when in reality it is not),
malingerers’ performance will drop further
(Binder, 1990; Hiscock & Hiscock, 1989).
With anterograde amnesia, practically any
memory test will give insight into
malingering. If performance is worse than
chance, or if worse than the baseline of
genuine amnesiacs with similar pathology,
there is cause for suspicion.
Nevertheless, this will not be conclusive
evidence of malingering, as there may be
confounding conditions (comorbidity) at
play, such as severe intellectual global
deficits (reduced cognitive deficits)
(Staniloui & Markowitsch, 2012) or dementia
(Teichner & Wagner, 2004).
A range of methods are available to assess the presence of malingering, with performance below chance or that of genuine amnesiacs is cause for suspicion.
However, by themselves no test can confidently conclude that malingering has taken place. Some methods, such as neuroscientific ones, may be logistically
difficult to employ. By establishing a consistently poor performance across a variety of tests, after excluding potentially confounding variables, there are good
grounds to suspect that a patient may be exaggerating or feigning his symptoms, pointing towards malingering.
As malingering is a form of lying, there is
also physical evidence available that give
cues as to whether or not malingering is
occurring. Simulators will show increased
pupil dilation when they recognise stimuli
(Heaver & Hutton, 2010). When maintaining
a lie, there is significantly more brain
activation in a large variety of areas
compared to telling the truth (Seron, 2014),
especially areas associated with executive
tasks (Christ et al., 2009).
When assessing retrograde amnesia, the
details of the event are largely out of the
experimenter’s control, making assessment
challenging. There are tests such as the
dead/alive test, where participants must
recall whether a person is dead or alive, and
how that person died. Again, malingerers
tend to perform worse than genuine
amnesiacs (Jenkins et al., 2009).
In some cases, inconsistencies in reports
may indicate malingering (Binder, 1990), or
reports from friends or relatives
contradicting the description given by the
suspected malingerer (Delis & Wetter,
2007).
Absolute certainty of malingering can only
be achieved through a confession.