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.

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.

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%.

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.

Accurate identification of Attention-Deficit/Hyperactivity Disorder (ADHD) is complicated by possible secondary gain, overlap of symptoms with psychiatric disorders, and face validity of measures (Suhr et al., 2011; Shura et al., 2017). To assist with diagnostic clarification, an experimental Dissimulation ADHD scale (Ds-ADHD; Robinson & Rogers, 2018) on the MMPI-2 was found to distinguish credible from non-credible respondents defined by Performance Validity Test (PVT)-based group assignment in Veterans (Burley et al., 2023). However, symptom and performance validity have been understood as unique constructs (Van Dyke et al., 2013), with Symptom Validity Tests (SVTs) more accurately identifying over-reporting of symptoms in ADHD (White et al., 2022). The current study sought to evaluate the effectiveness of the Ds-ADHD scale using an SVT, namely the Infrequency Index of CAARS (CII; Suhr et al., 2011), for group assignment within a mixed sample of Veterans.

In this retrospective study, 187 Veterans (Mage = 36.76, SDage = 11.25, Medu = 14.02, SDedu = 2.10, 83% male, 19% black, 78% white) were referred for neuropsychological evaluation of ADHD and administered a battery that included internally consistent MMPI-2 and CAARS profiles. Veterans were assigned to a credible group (n=134) if CII was <21 or a non-credible group (n=53) if CII was >21. The Ds-ADHD scale was calculated for the MMPI-2. Consistent with Robinson and Rogers (2018), “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.

Analyses revealed no significant differences in age, education, race, or gender (ps > .05) between credible and non-credible groups. An ANOVA indicated a significant difference between groups (F[1,185] = 24.78, p <.001; Cohen’s d = 0.80) for Ds-ADHD raw scores. Veterans in the non-credible group reported more “erroneous stereotypes” of ADHD (M raw score = 13.23, SD = 2.10) than those in the credible group (M = 14.94, SD = 2.13). A ROC analysis indicated AUC of .72 (95% CI = .64 to .80). In addition, a Ds-ADHD cut score of <12 resulted in specificity of 94.5% and sensitivity of 22.6%, whereas a cut score of <13 resulted in specificity of 85.8% and sensitivity of 50.9%. When analyzing other CII cut scores recommended in the literature, results were essentially similar. Specifically, analyses were repeated when group assignment was defined by cut score of CII<18 and by removing an intermediate group (CII = 18 to 21; n=24).

The Ds-ADHD scale demonstrated significant differences between credible and non-credible respondents in a Veteran population. Results suggest a cut score of <12 had adequate specificity (.95) with low sensitivity (.23). This is consistent with findings using PVTs for group assignment that indicated a cut score of <12 had adequate specificity (.92) with low sensitivity (.19; Burley et al., 2023). Taken together, findings suggest that the Ds-ADHD scale demonstrates utility in the dissociation of credible from non-credible responding. Further research should evaluate the utility of the scale in other clinical populations.

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.

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.

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).

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.