High specificity of the medical symptom validity test in patients with very severe memory impairment.

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.