ADHD polygenic risk predicts neural signatures of cognitive control: Evidence from midfrontal theta dynamics

Cognitive control mechanisms ensure goal-directedness in behaviour. Difficulties in cognitive control are well-established in conditions such as attention-deficit/hyperactivity disorder (ADHD) and autism. On the neural level, midfrontal theta (4-8 Hz) activity has emerged as a reliable correlate of cognitive control processes. Previous findings showed alterations in theta-based signals in both ADHD and autism, most notably an increase in the variability of theta phases across trials in cognitive control tasks, which was predictive of increased response time variability (RTV) as well. Crucially, recent work on twin studies has provided strong evidence for the genetic underpinning of these associations. Here, for the first time, we investigated whether polygenic scores (PGS) for ADHD and autism can predict RTV and EEG-derived theta-based measures of cognitive control in 454 participants. We found that PGS for ADHD, but not autism, accounted for a significant proportion of the variance in theta phase variability, captured via inter-trial coherence (ITC), in the well-standardised arrow-flanker task (2.5% of total variance, corresponding to 3.3% of the reliable variance). Furthermore, theta-ITC showed excellent test-retest reliability in our sample, indicating psychometric robustness, which in turn, further strengthens our findings. These results provide robust evidence linking genetic risk to neural measures and suggest that core dysregulation of the temporal coordination of control processes in ADHD is under genetic influence.