ADHD Children Take More Time to Inhibit Automatic Responses: A Comparison with Anxiety Disorders Using NEPSY-II

Background/Objectives: Attention deficit hyperactivity disorder (ADHD) and anxiety disorders (AD) are prevalent in childhood and adolescence, often presenting with overlapping symptoms. This study aimed to assess cognitive and executive functions—specifically attention, inhibition, and working memory—in children with ADHD, AD, and comorbid ADHD + AD. It also sought to identify potential neuropsychological markers that differentiate ADHD from AD and ADHD + AD comorbidity. Methods: Cognitive and executive functions were assessed in a sample of 48 school-age children and adolescents (aged 8–15 years) using the Wechsler Intelligence Scale for Children—Fourth Edition (WISC-IV) and the NEPSY-II battery. The MASC 2 self-report questionnaire was also used to assess anxiety symptoms. The participants were divided into three groups based on clinical diagnoses: ADHD, AD, and ADHD + AD. Results: No significant group differences emerged in cognitive performance, attention, or working memory. Significant differences emerged in inhibition performance, with children in the AD group demonstrating more efficient inhibition compared to both the ADHD and ADHD + AD groups. Children with ADHD showed longer response times. Better performance on inhibition tasks was associated with more severe anxiety symptoms. Conclusions: These findings suggest that anxiety may modulate specific aspects of executive functioning during tasks requiring attentional and inhibitory control. However, the complex interaction between ADHD and anxiety requires further investigation. This study underscores the importance of distinguishing ADHD from AD based on cognitive and executive profiles, particularly inhibition. In this context, it supports the routine use of the NEPSY-II in combination with the MASC 2 questionnaire to facilitate differential diagnosis in clinical practice.