High Specificity of the Medical Symptom Validity Test in Patients with Very Severe Memory Impairment

Abstract

Failure on effort tests usually implies insufficient effort to produce valid cognitive test scores. However, many people with very severe cognitive impairment, such as dementia patients, will produce failing scores on nearly all effort tests. In such patients, effort tests have low specificity. The Medical Symptom Validity Test (MSVT) and the nonverbal MSVT (NV-MSVT) were designed to address this problem. They produce profiles of scores across multiple subtests to facilitate discrimination between low scores from people trying to feign impairment and low scores attributable to severe impairment. To study the specificity of the MSVT and NV-MSVT in people with very severe memory impairment, we tested (a) 10 institutionalized patients with dementia and (b) 10 volunteers who were asked to simulate memory impairment. It was hypothesized that the "possible dementia profile" would be found significantly more often in the dementia patients than in the simulators. The MSVT and the NV-MSVT both displayed 100% specificity in the dementia group, while retaining a combined sensitivity of 80% to suboptimal effort in the simulator group.

Sensitivity of the Test of Memory Malingering and the Nonverbal Medical Symptom Validity Test: A Replication Study

“…The profile makes intuitive sense, in that performances on the more difficult subtests (i.e., non-forced-choice recognition and free recall trials) are much worse than performances on easier subtests (i.e., various forced-choice trials). These profiles have been observed in other samples with dementia (Henry, Merten, Wolf, & Harth, 2009;Singhal, Green, Ashay, Shankar, & Gill, 2009). Greater detail regarding the specificity of the NV-MSVT can be found elsewhere (e.g., Green, 2011).…”

“…If Criterion A and any of Criteria B1, B2, or B3 are failed, the examinee is judged to be giving poor effort. The sensitivity and specificity of these decision rules have been supported across multiple studies (Green, 2008;Green, Flaro, Brockhaus, & Montijo, 2010;Henry et al, 2009;Singhal et al, 2009).…”

“…The final subtest is a free recall task where the examinee is asked to recall from memory as many items from the original list of paired items as possible. The sensitivity and specificity of the NV-MSVT have been demonstrated in a variety of patient populations (Green, 2008;Henry et al, 2009;Singhal et al, 2009).…”

“…By demonstrating these types of profiles, those individuals who failed the NV-MSVT but passed the TOMM evidenced results that are inconsistent across the various NV-MSVT subtests that differ in objective difficulty. These profiles are typical of simulators but are very infrequently seen in people with genuine memory impairment (Green, 2011(Green, , 2008Henry et al, 2009;Singhal et al, 2009). Of particular interest is what Green (2011) refers to as a ''paradoxical profile.''…”

“…The NV-MSVT is similar to the MSVT and WMT in that the measure possesses a range of subtests that demonstrate a gradient of difficulty and these subtests allow for a profile analysis. The use of such profile analysis has been shown to achieve high sensitivity to poor effort in simulators and high specificity in people with severe impairment (Green, 2007(Green, , 2008Henry et al, 2009;Singhal et al, 2009). In the Green (2011) study, profile analysis demonstrated that for those who failed the NV-MSVT but passed the TOMM, the pattern of results better matched simulator samples rather than samples with actual severe impairment.…”