The Impact of Sex on Cognitive Control in ADHD: Girls Slow to Inhibit, Boys Inhibit Less, and Both Show Higher Response Variability

Objective: To determine whether girls and boys with ADHD show distinct impairments in components of cognitive control across multiple tasks (go/no-go, stop signal, and flanker) and performance metrics (response speed, variability, and errors). Method: A total of 300 children, ages 8 to 12 years with ADHD (n = 210, 58 girls) or typically developing (TD; n = 99, 37 girls), completed all tasks. Traditional response measures (e.g., mean and standard deviation of reaction time, inhibition errors, and stop signal reaction time) and ex-Gaussian modeling of reaction times (mu, sigma, and tau) were analyzed. Results: Girls showed intact response inhibition in the context of slower response speed, while boys made more inhibition errors and did not slow their response speed. Both girls and boys with ADHD showed higher response variability and poorer interference control than TD children. Conclusion: Girls and boys with ADHD show distinct impairments in cognitive control that may be important for understanding the pathophysiology of ADHD.