Symptom validity test performance in the Huntington Disease Clinic

Abstract

Symptom validity tests (SVTs) are often used in neuropsychological assessment; however, recent studies indicate that cognitive impairment/dementia may contribute to failing scores on some effort tests. The purpose of this study was to characterize how individuals with Huntington disease (HD) perform on three SVTs and to examine the relationship between SVT performance and demographic and clinical variables. Results indicate that while the majority of HD patients passed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Effort Index (EI; 82% of n = 121) and the Test of Memory Malingering (92% of n = 36), failure of these SVTs was associated with poorer cognitive and adaptive functioning, and greater motor impairment. Results showed that less than one-third passed the RBANS Effort Scale (ES; 30% of n = 43) and few clinical and demographic variables were correlated with this SVT performance. Although some SVTs may be better suited to HD, cognitive ability should be considered when evaluating effort in HD.

Fig. 1.

Relationship between SVT scores and RBANS Total score. The three panels illustrate the relationship between each SVT score and RBANS Total score. The range of possible scores for each SVT is shown on the x-axis. RBANS Total scores are shown on the y-axis. Published SVT cut-scores are as follows: EI Pass ≤ 3 (lower scores suggest better effort); ES Pass ≥ 12 (higher scores suggest better effort); TOMM Pass ≥ 45 (higher scores suggest better effort).