8 Detection of Feigned ADHD through an Experimental MMPI-2 ADHD Validity Scale among U.S. Military Veterans

Abstract

Objective:

The prevalence of ADHD diagnoses more than doubled in VA settings between 2009 and 2016 (Hale et al., 2020). However, attentional difficulties are not exclusive to ADHD and can also be seen in non-neurodevelopmental disorders, including depression, anxiety, substance use, and PTSD (Marshall et al., 2018, Suhr et al., 2008). Further, patients can easily feign symptoms of ADHD with few available instruments for accurate detection (Robinson & Rogers, 2018). Given the significant symptom overlap and rising rates of reported ADHD among Veterans, accurate detection of feigned ADHD is essential.

This study examined the utility of the experimental Dissimulation ADHD scale (Ds-ADHD; Robinson & Rogers, 2018) on the MMPI-2, in detecting feigned ADHD presentation within a mixed sample of Veterans.

Participants and Methods:

In this retrospective study, 173 Veterans (Mage = 36.18, SDage = 11.10, Medu = 14.01, SDedu = 2.11, 88% male, 81% White, and 17% Black) were referred for neuropsychological evaluation of ADHD that included the MMPI-2 and up to 10 PVTs. Participants were assigned to a credible group (n=146) if they passed all PVTs or a non-credible group (n=27) if they failed two or more PVTs. Group assignment was also clinically confirmed. The Ds-ADHD was used to differentiate groups who either had credible or non-credible performance on cognitive measures. Consistent with Robinson and Rogers’ study, “true” answers (i.e., erroneous stereotypes) were coded as 1 and “false” answers were coded as 2, creating a 10- to 20-point scale. Lower scores were associated with a higher likelihood of a feigned ADHD presentation.

Results:

Preliminary analyses revealed no significant group differences in age, education, race, or gender (ps > .05). An ANOVA indicated a significant difference between groups (F[1, 171] = 10.44, p = .001; Cohen’s d = .68) for Ds-ADHD raw scores; Veterans in the non-credible group reported more “erroneous stereotypes” of ADHD (M raw score = 13.33, SD = 2.20) than those in the credible group (M = 14.82, SD = 2.20). A ROC analysis indicated AUC of .691 (95% CI = .58 to .80). In addition, a cut score of <12 resulted in specificity of 91.8% and sensitivity of 18.5%, whereas a cut score of <13 resulted in specificity of 83.6% and sensitivity of 44.4%.

Conclusions:

The Ds-ADHD scale demonstrated significant differences between credible and non-credible respondents in a real-world setting. Previously, this scale has primarily been studied within laboratory settings. Further, results indicate a cut score of <12 could be used in order to achieve adequate specificity (i.e., >90%), which were similar findings to a study examining SVT-based groups (Winiarski et al., 2023). These results differ slightly from prior research by Robinson and Rogers (2018), who indicated a cut score of <13 based on the initial simulation-based study. In similar clinical settings, where there are high rates of psychiatric comorbidity, a cut score of <12 may prove clinically useful. However, this cut-score was associated with low sensitivity within this mixed Veteran sample. Further research should focus on replicating findings within other clinical settings, including ones with larger non-credible samples.