Intra-Subject Variability, Intelligence, and ADHD Traits in a Community-Based Sample

Objective: The present study investigates the predictive validity of intra-subject variability (ISV) for ADHD traits in a community-based sample and the stability of the relationship between ISV and fluid intelligence (gf) across the continuum of ADHD traits. Method: Age-residualized data from 426 participants (8-18 years, 6% ADHD) was used to investigate whether ex-Gaussian and DDM parameters derived from simple choice-reaction-time tasks can predict continuously assessed ADHD traits. Multiple-Group-Analyses and Latent-Moderated-Structural-Equations were used to test whether ADHD traits moderate the relationship between ISV and gf. Results: sigma and mu of the ex-Gaussian model as well as DDM parameters drift rate (v) and boundary separation (a) significantly predicted general ADHD traits, while tau predicted attention difficulties specifically. Across the ADHD continuum, sigma and v were significant predictors of gf. Conclusion: The results confirm the link between ISV and ADHD. The relationship between ISV and gf appears stable across the ADHD continuum.