Cognitive and perceptual load have opposing effects on brain network efficiency and behavioral variability in ADHD

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder associated with suboptimal outcomes throughout the life-span. Extant work suggests that ADHD-related deficits in task performance may be magnified under high cognitive load and minimized under high perceptual load, but these effects have yet to be systematically examined, and the neural mechanisms that undergird these effects are as yet unknown. Herein, we report results from three experiments investigating how performance in ADHD is modulated by cognitive load and perceptual load during a naturalistic task. Results indicate that cognitive load and perceptual load influence task performance, reaction time variability (RTV), and brain network topology in an ADHD-specific fashion. Increasing cognitive load resulted in reduced performance, greater RTV, and reduced brain network efficiency in individuals with ADHD relative to those without. In contrast, increased perceptual load led to relatively greater performance, reduced RTV, and greater brain network efficiency in ADHD. These results provide converging evidence that brain network efficiency and intraindividual variability in ADHD are modulated by both cognitive and perceptual load during naturalistic task performance. Attention-deficit/hyperactivity disorder (ADHD) affects more than 500 million adults worldwide (Song et al., 2021), and confers suboptimal outcomes in many areas of life. Emerging evidence suggests that ADHD-related cognitive deficits may be at least somewhat task-dependent, with some work showing that increased cognitive load results in reduced performance in ADHD relative to non-ADHD individuals, and other work showing that increased perceptual load may narrow, or even eliminate these deficits. However, these effects have yet to be examined together, and their neural underpinnings are unknown. In three experiments (one in the lab, one online, and one fMRI), we show that cognitive load worsens cognitive performance, and reduces brain network efficiency in ADHD relative to non-ADHD individuals, while perceptual load has largely the opposite effect.