Effects of Korsakoff Amnesia on performance and symptom validity testing

Performance validity tests (PVTs) and Symptom validity tests (SVTs) are developed to identify people that present false or exaggerated symptoms. Although a key factor of both types of tests includes relative insensitivity to cognitive disorders, the direct effects of amnesia have been poorly studied. Therefore, a sample of 20 patients diagnosed with Korsakoff Amnesia (KA) through neuropsychological assessment and 20 healthy comparisons (HC) were administered the Test of Memory Malingering (TOMM), the Structured Inventory of Malingered Symptomatology (SIMS), and the newly developed Visual Association Test - Extended (VAT-E). Our results show that KA patients scored systematically lower on the TOMM and VAT-E, while performance on the SIMS was comparable with healthy comparisons. Some KA patients were regarded as underperformers based on the TOMM and VAT-E, suggesting limitations in applying these instruments in severe amnesia. There was a strong interdependence of PVTs in logistic regression. We conclude that the TOMM and VAT-E are not fully robust against severe memory disorders and show a serious risk of false positives. Complete neuropsychological profile analysis is needed, and PVTs should be interpreted with caution in patients with suspected amnesia.