Probing the overarching continuum theory: Data-driven phenotypic clustering of children with ASD or ADHD

Abstract

The clinical validity of the distinction between ADHD and ASD is a longstanding discussion. Recent advances in the realm of data-driven analytic techniques now enable us to formally investigate theories aiming to explain the frequent co-occurrence of these neurodevelopmental conditions. In this study, we probe different theoretical positions by means of a pre-registered integrative approach of novel classification, subgrouping and taxometric techniques in a representative sample (N=434) and replicate the results in an independent sample (N=219) of children (ADHD, ASD, and typically developing) aged 7 to 14 years. First, Random Forest Classification could predict diagnostic groups based on questionnaire data with limited accuracy - suggesting some remaining overlap in behavioural symptoms between them. Second, community detection identified four distinct groups, but none of them showed a symptom profile clearly related to either ADHD or ASD in neither the original sample nor the replication sample. Third, taxometric analyses showed evidence for a categorical distinction between ASD and typically developing children, a dimensional characterization of the difference between ADHD and typically developing children and mixed results for the distinction between the diagnostic groups. We present a novel framework of cutting-edge statistical techniques which represent recent advances in both the models and the data used for research in psychiatric nosology. Our results suggest that that ASD and ADHD cannot be unambiguously characterised as either two separate clinical entities or opposite ends of a spectrum and highlight the need to study ADHD and ASD traits in tandem.

The distribution of parent‐reported attention‐deficit/hyperactivity disorder and subclinical autistic traits in children with and without an ADHD diagnosis

“…We found that ADHD and autistic traits formed two distinct factors as hypothesised. Next, and consistent with existing literature (e.g., Deserno et al., 2022; Posner et al., 2020), the distribution of CPRS ratings in both our samples supported the description of ADHD as a continuum extending from neurotypical profiles. We were also able to successfully replicate a 2‐factor, 2‐class FMM‐3 model in two independent samples based on responses to the AQ and CPRS.…”