SUMMARY Critical evaluation of tests for malingered TBI is still awaited. Unexpectedly poor and inconsistent results on certain tests may be evidence of intentionally inferior effort.
Estimates of the prevalence of malingering in Traumatic Brain Injury (TBI) range from 1 to 50% 1.
Routine neuropsychological testing cannot reliably demonstrate malingered brain injury 2. However, the astute neuropsychologist will pick up clues that specific testing for malingering is required.
In particular, malingerers as a group are more sophisticated in simulating impairment in verbal tasks than in nonverbal or timed tests. Typically they "aim too low" in estimating how much brain injury compromises nonverbal or timed performance.
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PRACTICE POINT Standard neuropsychological testing
cannot identify malingering, but can alert the tester
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Critical evaluation of tests for malingered TBI is still awaited. In contrast with chronic benign pain, exhaustive meta-analysis of tests for malingering in Mild Traumatic Brain Injury (MTBI) has not yet been undertaken.
Though there are papers reviewing and critiquing individual psychological instruments, comprehensive assessment of the reliability of such testing is lacking. Moreover, it is not clear to what extent the results of experiments in which subjects are asked to simulate or exaggerate can be generalised to malingered brain injury in the medicolegal environment2.
There is, however, a growing body of evidence 3 that certain forced-choice tests are most sensitive and specific for one-time examination, and other promising methods are currently under evaluation.
The Portland Digit Recognition Test and the Victoria Symptom Validity Test are among the currently established single examination methods for best detection of malingered brain injury.
Unexpectedly poor and inconsistent results on certain tests may be evidence of intentionally inferior effort.
On a one-time battery of psychological instruments routinely used to detect malingering, those subjects who had been asked to simulate head injury were clearly distinguishable3 from normal controls.
However, first, second and third spaced repetitions of the Symptom Validity Test (SVT) in particular produced such inconsistent scores in simulators that this variability has been proposed as a basis for detecting malingering.
The authors caution that there is some evidence that, at least in the early stages of recovery from MTBI, particularly that involving the frontal lobes, variability on repeat retesting distinguishes the genuinely brain-injured from normal control subjects. It remains to be determined whether that variability is different in kind and extent.
The Word Memory Test examines the ability to learn a list of 20 pairs of semantically-related common words. The words uniformly require a low reading ability and, though the Immediate Recognition and Delayed Recognition subtests seem difficult, they are easily passed by patients with severe head injury.
By contrast, more than a quarter of MTBI claimants performed so poorly that the mean average score for the whole group was significantly worse than that of a control group of patients whose much severer TBI had been accepted for compensation 4.
This paradoxical superiority of test scores in patients with more severe brain injuries is seen in other tests that have been used to validate measures of biased responding - Computerized Assessment of Response Bias (CARB) 5 and Warrington Recognition Memory Test 6. The counter-intuitive results are currently thought to be a reliable measure of intentionally poor effort.
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PRACTICE POINT Malingered MTBI may be
detected by
1. Inconsistency on repeat retesting 2. Easy tests that seem hard |
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