On the limits of effort testing: Symptom validity tests and severity of neurocognitive symptoms in nonlitigant patients

Abstract

Modern symptom validity tests (SVTs) use empirical cutoffs for decision making. However, limits to the applicability of these cutoffs may arise when severe cognitive symptoms are present. The purpose of the studies presented here was to explore these limits of applicability. In Experiment 1, a group of 24 bona fide neurological patients without clinically obvious cognitive symptoms was compared to a group of 24 patients with rather severe symptoms. A comprehensive test battery was employed, which included four SVTs (the Test of Memory Malingering, TOMM, the Word Memory Test, WMT, the Bremer Symptomvalidierung, BSV, and the Amsterdam Short-Term Memory Test, ASTM). In Experiment 2, a group of 20 patients with mild Alzheimer's disease was compared to 14 healthy controls. Results of both studies showed that cognitive impairment may significantly interfere with SVT performance. Correlation analyses revealed dissimilar relationships between SVTs and neuropsychological test measures. Whereas TOMM and WMT correlated mainly with tests of declarative memory, the BSV correlated with tests of attention, and ASTM correlated with tests of working memory. Intercorrelations between symptom validity measures were relatively low. The published cutoffs of the TOMM would be suitable for estimating effort in patients with Mini-Mental State Examination scores of 24 or above. More research will be necessary to investigate how performance in SVTs is related to cognitive functioning in populations of severely impaired patients.

Symptom Validity Testing in Claimants with Alleged Posttraumatic Stress Disorder: Comparing the Morel Emotional Numbing Test, the Structured Inventory of Malingered Symptomatology, and the Word Memory Test

“…From the WAIS-III subtest Digit Span (Wechsler 1997), the Reliable Digit Span (RDS) was computed according to the procedure described by Greiffenstein et al (1994). RDS has repeatedly been used as a symptom validity measure, but classification results have usually been modest in comparison with special SVTs (e.g., Merten et al 2007a). …”

“…Previous research on intercorrelations between pairs of different cognitive SVTs and between cognitive and psychological validity measures (e.g., Inman and Berry 2002;Merten et al 2007a;Nelson et al 2003;Ruocco et al 2008) suggested also that there might be small to moderate associations between pairs of symptom validity measures (hypothesis II), according to the guidelines proposed by Cohen (1988). If both hypotheses are corroborated by the data, this would, in the authors' opinion, support a multi-method approach to symptom validity assessment in claimants with alleged PTSD.…”

The effect of distraction on the Word Memory Test and Test of Memory Malingering performance in patients with a severe brain injury

“…The remaining 7 had coma durations of greater than one week. All of the nTBI participants (n 5 22) were considered severely brain damaged under the Merten et al (2007) criteria of "clinically obvious symptoms," including repeated speech, bradyphrenia and word finding difficulties. Aetiology of these injuries included stroke (n 5 11), poisoning (n 5 3), hypoxia (n 5 3) tumor (n 5 2) or other causes (n 5 3).…”

“…The WMT "effort" measures have been described as being "virtually insensitive to all but the most extreme forms of impairment of learning and memory" (Green et al, 2002, p. 99). Whereas the test authors have argued that failure on the WMT is caused by lack of "effort", Merten et al (2007) have suggested that in patients with clinically obvious symptoms, scores below cut-offs do not always provide information about insufficient "effort" but rather may simply represent false positives.…”

Traumatic Brain Injury Alters Word Memory Test Performance by Slowing Response Time and Increasing Cortical Activation: An fMRI Study of a Symptom Validity Test

“…Despite its apparent ease, however, the WMT does require neurocognitive resources and is thus potentially susceptible to failure due to underlying neural dysfunction. For example, individuals with memory disorders associated with some types of degenerative disease may "fail" the WMT (i.e., perform below established cut-score levels; see Merten et al 2007) as do some patients with TBI (Flaro et al 2007). Likewise, patients with major neuropsychiatric disorders like schizophrenia also exhibit a high WMT failure rate (Gorissen et al 2005).…”