Differential response to pharmacological intervention in ADHD furthers our understanding of the mechanisms of interference control

Dissociable effects of positive feedback on the capture and inhibition of impulsive behavior in adolescents with ADHD versus typically developing adolescents

The present study investigated how enhancing motivation by delivering positive feedback (a smiley) after a successful trial could affect interference control in adolescents with Attention Deficit Hyperactivity Disorder (ADHD) and in their typically developing (TD) peers. By using a Simon task within the theoretical framework of the "activation-suppression" model, we were able to separately investigate the expression and the inhibition of impulsive motor behavior. The experiment included 19 adolescents with ADHD and 20 TD adolescents in order to explore whether data found in adolescents with ADHD were similar to those found in TD adolescents. Participants performed the Simon task in two conditions: a condition with feedback delivered after each successful trial and a condition with no feedback. The main findings were that increasing motivation by delivering positive feedback increased impulsive response in both groups of adolescents. It also improved the efficiency of impulsive motor action inhibition in adolescents with ADHD but deteriorated it in TD adolescents. We suggest that 1/increased motivation could lead adolescents to favor fast responses even if incorrect, and 2/the differential effect of feedback on the selective suppression of impulsive motor action in both groups could be due to different baseline DA levels.

The effect of reducing attentional resources on selective suppression in the Simon task

Studies using reaction times (RTs) distribution methods find that the Simon effect is greater for fast RTs and becomes smaller or reversed for slow RTs. However, the exact mechanisms responsible for this reduction are under debate. This study addressed the issue of whether attentional resources play a role in reduction of the Simon effect over time by investigating whether it is influenced by attentional constraints in a dual-task paradigm. Participants were instructed to perform a Simon task concurrently with a secondary task. Secondary task characteristics were manipulated by varying the overlap between the secondary task and the Simon task. Specifically, secondary tasks varied in their stimulus modality (auditory or visual) and/or response type (verbal or manual and lateralised or not). Distribution analyses of RTs, in the form of delta-plot functions, were performed for both the single- and dual-task conditions. Results showed that the more attention the secondary task demanded, the less the Simon effect was reduced, even for slower RTs. This suggests that the mechanisms responsible for the reduction of Simon effect over time are under top-down control.

Effects of Physical Activity on Inhibitory Function in Children with Attention Deficit Hyperactivity Disorder: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to systematically evaluate the effect of physical activity (PA) on inhibitory function in children with ADHD. Experimental studies on the effect of PA on the inhibitory function of children with ADHD were retrieved. The data were obtained from PubMed, The Cochrane Library, Web of Science, EBSCO (MEDLINE, APA Psyclnfo, ERIC), Embase, Scopus, and ProQuest. The search period was from the date of inception of the respective databases to 4 May 2022, and Reviewer Manager software (version 5.3) was used for analysis. Eleven articles and 713 samples were included in the meta-analysis. Results revealed that PA can significantly improve the inhibitory function of children with ADHD (SMD = 0.78, 95% CI: 0.45−1.10, p < 0.001). Subgroup analysis showed that the effectiveness of PA as an intervention in improving the inhibitory function of children with ADHD was moderated by the frequency, intensity, duration, type, and length of intervention. Based on the findings, PA can effectively improve interference suppression inhibitory function in children with ADHD. Longitudinal open-skill exercise for 60 min or more, two times/week has the best effect on improving inhibitory function in children with ADHD.

Two sides of the same coin: ADHD affects reactive but not proactive inhibition in children

Children with attention-deficit/hyperactivity disorder (ADHD) present a deficit in inhibitory control. Still, it remains unclear whether it comes from a deficit in reactive inhibition (ability to stop the action in progress), proactive inhibition (ability to exert preparatory control), or both.We compared the performance of 39 children with ADHD and 42 typically developing children performing a Simon choice reaction time task. The Simon task is a conflict task that is well-adapted to dissociate proactive and reactive inhibition. Beyond classical global measures (mean reaction time, accuracy rate, and interference effect), we used more sophisticated dynamic analyses of the interference effect and accuracy rate to investigate reactive inhibition. We studied proactive inhibition through the congruency sequence effect (CSE).Our results showed that children with ADHD had impaired reactive but not proactive inhibition. Moreover, the deficit found in reactive inhibition seems to be due to both a stronger impulse capture and more difficulties in inhibiting impulsive responses. These findings contribute to a better understanding of how ADHD affects inhibitory control in children.