Abstract

This study aimed to explore the characteristics of cognitive control deficits in adult ADHD from the perspective of Dual Mechanism of Control (DMC), which posits that cognitive control operates via two distinct dimensions, i.e., proactive and reactive control. AX-CPT, including nogo trials, was utilized to tap cognitive control processes in a sample of 27 adults with ADHD, 17 adults with depression, and 29 healthy adults. The performance of adults with ADHD was compared to that of adults with depression as well as healthy adults to investigate the effects of depression, which is a common comorbid condition in adult ADHD. AX-CPT is a continuous performance test consisting of four types of cue-probe pairs (AX, AY, BX, BY) and requires participants to respond to a probe based on a preceding cue. AX pairs are target pairs matched with a target response, and other pairs are non-target pairs matched with a non-target response. The proactive control demands were manipulated with the proportion of AX trials(AX-40 vs. AX-70) and the reactive control demands were manipulated with nogo trials(base vs. nogo). The order of the two AX-proportion conditions were counterbalanced, and the base condition and the nogo condition were implemented in order within each AX-proportion condition. The adult ADHD group showed lower accuracy than the depression group and the healthy control group in the performance of BX trials that require proactive inhibitory control. Both the ADHD group and the depression group performed lower than the healthy control group in nogo trials that require reactive inhibitory control. These results suggest that adults with ADHD have a deficit in overall cognitive control, including proactive and reactive control, and the reactive control deficit of adult ADHD may be associated with comorbid depression as well as ADHD itself.