31 The ADHD Dissimulation Scale (Ds- ADHD) on the MMPI-2-RF versus Established MMPI-2-RF Validity Scales

Abstract

Objective:

The MMPI-2-RF contains scales that assess different types of invalid response styles, especially potential symptom over-reporting (e.g., F-r, Fs, Fp-r, FBS-r, RBS). However, these scales are not designed to specifically capture noncredible symptoms reports associated with Attention-Deficit/Hyperactivity Disorder (ADHD). Robinson & Rogers (2018) proposed the experimental Dissimulation ADHD validity scale (Ds-ADHD) on the MMPI-2-RF that was effective in distinguishing credible and non-credible ADHD diagnoses via a simulator-based study. Within the current study, the Ds-ADHD scale was compared to the established MMPI-2-RF validity scales within a mixed sample of U.S. Military Veterans.

Participants and Methods:

173 Veterans (Mage = 36.18, SDage = 11.10, Medu = 14.01, SDedu = 2.11, 88% male, 81% White, 17% Black) completed a neuropsychological evaluation which included an internally consistent MMPI-2-RF profile and up to 10 performance validity tests (PVTs) as well as a question about a possible ADHD diagnosis. The credible group was determined if participants passed all PVTs (n=146) and completed at least 2 PVTs. The non-credible group was determined by failing two or more PVTs (n=27). Group assignment was clinically confirmed. The Ds-ADHD scale was calculated according to Robinson & Rogers’ (2018); responses of “true” (i.e., erroneous stereotypes) were coded as 1 and “false” answers were coded 2, creating a 10- to 20-point scale. Thus, lower scores would be associated with a higher likelihood of a feigned ADHD presentation. Other MMPI-2-RF validity scales of interest included F-r, Fs, Fp-r, FBS-r, and RBS.

Results:

The established MMPI-2-RF validity scales were significantly correlated with PVT group membership, but correlations were weak to moderately strong (rS ranged from -.43 to -.18; ps < .05). A series of stepwise regression models were completed with the Ds-ADHD scale and one of the MMPI-2-RF validity scales as independent variables, with group membership as the dependent variable. Ds-ADHD) contributed uniquely to each model (CÜ ranged from .03 to .04, ps < .05). The established MMPI-2-RF validity scales effectively classified group membership (AUC values ranged from .57 to .68), and the Ds-ADHD scale had a marginally higher AUC (.69); however, it was not statistically significantly stronger than any of the established scales (ps > .05).

Conclusions:

Clinicians interested in identifying potentially simulated ADHD presentations with the MMPI-2-RF may desire to calculate the Ds-ADHD scale, which previously only had support from a simulator-based study. The Ds-ADHD scale significantly contributed to each model, suggesting that it helped explain groups over and above each of the traditional MMPI-2-RF validity scales. However, it only had a marginally stronger ability to classify participants, indicating that there may be diminishing returns for clinicians. Among the traditional validity scales, RBS and F-r best classified groups, and FBS-r was the least effective. This study employed a cross-sectional design in a mixed sample of Veterans undergoing a neuropsychological evaluation. Future research should focus on replicating the findings using a credible sample that was limited to an independently verified diagnosis of ADHD.