Non-credible symptom report in the clinical evaluation of adult ADHD: development and initial validation of a new validity index embedded in the Conners’ adult ADHD rating scales

Abstract

As attention-deficit/hyperactivity disorder (ADHD) is a feasible target for individuals aiming to procure stimulant medication or accommodations, there is a high clinical need for accurate assessment of adult ADHD. Proven falsifiability of commonly used diagnostic instruments is therefore of concern. The present study aimed to develop a new, ADHD-specific infrequency index to aid the detection of non-credible self-report. Disorder-specific adaptations of four detection strategies were embedded into the Conners’ Adult ADHD Rating Scales (CAARS) and tested for infrequency among credible neurotypical controls (n = 1001) and credible adults with ADHD (n = 100). The new index’ ability to detect instructed simulators (n = 242) and non-credible adults with ADHD (n = 22) was subsequently examined using ROC analyses. Applying a conservative cut-off score, the new index identified 30% of participants instructed to simulate ADHD while retaining a specificity of 98%. Items assessing supposed symptoms of ADHD proved most useful in distinguishing genuine patients with ADHD from simulators, whereas inquiries into unusual symptom combinations produced a small effect. The CAARS Infrequency Index (CII) outperformed the new infrequency index in terms of sensitivity (46%), but not overall classification accuracy as determined in ROC analyses. Neither the new infrequency index nor the CII detected non-credible adults diagnosed with ADHD with adequate accuracy. In contrast, both infrequency indices showed high classification accuracy when used to detect symptom over-report. Findings support the new indices’ utility as an adjunct measure in uncovering feigned ADHD, while underscoring the need to differentiate general over-reporting from specific forms of feigning.

Joint Consideration of Validity Indicators Embedded in Conners’ Adult ADHD Rating Scales (CAARS)

“…The study design and data set described here were adapted from Becke et al (2021) to investigate the previously unexamined, combined consideration of multiple validity indicators. For this purpose, participant selection and methods were modified as outlined in the following sections.…”

“…The diagnostic procedure, therefore, followed criteria for firsttime adult ADHD diagnosis (e.g., see Sibley, 2021). As outlined in our previous study (Becke et al, 2021), where this sample was first described, a comprehensive clinical work-up conducted by at least two experienced clinicians secured their diagnoses. It included a psychiatric interview which enquired both past and present symptoms and impairments of ADHD as laid out in the DSM (American Psychiatric Association, 2000Association, , 2013Barkley & Murphy, 1998), as well as the completion of two standardized self-report rating scales which tapped symptoms of ADHD across the same period (WURS-K and ASR) (Adler et al, 2006;Kessler et al, 2005;Ward et al, 1993).…”

“…More recent developments include the Dissimulation ADHD Scale (Ds-ADHD) introduced by Robinson and Rogers (2018), the ADHD Symptom Infrequency Scale (ASIS) with its Infrequency Scale (INF) (Courrégé et al, 2019), and the ADHD Credibility Index (ACI) (Becke et al, 2021). They share a common conceptual basis in that all three scales tap misconceptions about ADHD.…”

“…Despite comparable sensitivity, early data on the ACI indicate that it may identify a different subset of feigning individuals than the CII (Becke et al, 2021). Given that different validity indicators detect different cases of non-credible self-report, considering multiple indicators jointly could increase sensitivity to instances of feigned ADHD.…”

Brain Relatively Inert Network: Taking Adult Attention Deficit Hyperactivity Disorder as an Example

“…Due to misunderstandings and lack of knowledge about this disease, many people with ADHD are misdiagnosed and often fail to receive effective treatment ( Kooij et al, 2010 ). At the same time, the falsifiability based on the diagnostic scales is also very worrying ( Smith et al, 2017 ; Becke et al, 2021 ). Therefore, the diagnosis of adult ADHD is more difficult compared with childhood ADHD.…”