10 The Impact of Performance and Symptom Invalidity on Relationships Between Subjective and Objective Cognitive Functioning

Abstract

Objective:

Inconsistent relationships between subjective and objective performance have been found across various clinical groups. Discrepancies in these relationships across studies have been attributed to various factors such as patient characteristics (e.g., level of insight associated with cognitive impairment) and test characteristics (e.g., using too few measures to assess different cognitive domains). Although performance and symptom invalidity are common in clinical and research settings and have the potential to impact responding on testing, previous studies have not explored the role of performance and symptom invalidity on relationships between objective and subjective performance. Therefore, the current study examined the impact of invalidity on performance and symptom validity tests (PVTs and SVTs, respectively) on the relationship between subjective and objective cognitive functioning.

Participants and Methods:

Data were obtained from 299 Veterans (77.6% male, mean age of 48.8 years (SD = 13.5)) assessed in a VA medical center epilepsy monitoring unit from 2008-2018. Participants completed a measure of subjective functioning (i.e., the Patient Competency Rating Scale), PVTs (i.e., Word Memory Test, Test of Memory Malingering, Reliable Digit Span), SVTs (i.e., Minnesota Multiphasic Personality Inventory-2-Restructured Form Response Bias Scale, Structured Inventory of Malingered Symptomatology), and neuropsychological measures assessing objective cognitive performance (e.g., Trail Making Test parts A and B). Pearson correlations were conducted between subjective functioning and objective cognitive performance in the following groups: 1.) PVT and SVT valid, 2.) PVT and SVT invalid, 3.) PVT-only invalid, 4.) SVT-only invalid. Using Fisher’s r-to-z transformation, tests for the differences between correlation coefficients were then conducted between the PVT and SVT valid vs. PVT and SVT invalid groups, and the PVT-only invalid vs. SVT-only invalid groups.

Results:

Participants with fully valid PVT and SVT performances demonstrated generally stronger relationships between subjective and objective scores (r’s = .058 - .310) compared to participants with both invalid PVT and SVT scores (r’s = -.033 - .132). However, the only significant difference in the strengths of correlations between the groups was found on Trail Making Test Part B (p = .034). In separate exploratory analyses due to low group size, those with invalid PVT scores only (fully valid SVT) demonstrated generally stronger relationships between subjective and objective scores (r’s = -.101 - .741) compared to participants with invalid SVT scores only (fully valid PVT; r’s = -.088 - .024). However, the only significant difference in the strengths of correlations between the groups was found on Trail Making Test Part A (p = .028).

Conclusions:

The present study suggests that at least some of the discrepancies in previous studies between subjective and objective cognitive performance may be related to performance and symptom validity. Specifically, very weak relationships between objective and subjective performance were found in participants who only failed SVTs, whereas relationships were stronger in those who only failed PVTs. Therefore, findings suggest that including measures of PVTs and SVTs in future studies investigating relationships between subjective and objective cognitive performance is critical to ensuring accuracy of conclusions that are drawn.