Differentiating malingering from genuine cognitive dysfunction using the Trail Making Test-ratio and Stroop...

Patterns of test performance that are inconsistent with knowledge of brain dysfunction can potentially differentiate between malingering and true impairment among litigants with low scores on neuropsychological tests. In this study possible malingerers (n = 41), impaired (30) or cognitively normal (17) litigants were compared on the Trail Making Test B:A ratio score and Stroop Interference. The majority of possible malingerers had a low TMT-ratio (<2.5) and an inverted Stroop effect, whereas the majority of impaired subjects had a high TMT-ratio and specific Stroop interference. Sensitivity to malingering was 61 and 68 percent, and specificity was 57 and 59 percent. This is too low for valid classification of individuals. However, the combination of both measures increases predictability. The clinician is advised to look for other evidence of malingering in cases of simultaneous low TMT-ratio and inverted Stroop. Patients with high TMT-ratio and Stroop interference, should be thoroughly examined for indications of brain disease.