Salivary cortisol as a stress biomarker and its association with executive functioning in pediatric ADHD

Abstract

Introduction Attention-deficit/hyperactivity disorder (ADHD) is associated with deficits in executive functions and alterations in physiological stress regulation. However, the relationship between stress-related biological markers and executive performance in children and adolescents with ADHD remains poorly understood.

Objectives This study aimed to compare executive functioning between children and adolescents with ADHD and typically developing controls; examine group differences in salivary cortisol levels and global stress indices; and explore the interaction between physiological stress regulation and executive performance.

Methods Participants were children and adolescents aged 6–16 years, including a control group (CT; n=43) and an ADHD group (n=48). Executive functions were assessed using the ENFEN battery. Salivary cortisol was collected at multiple time points, focusing on T1 (30 minutes before testing), T2 (test onset), and T3 (test completion), as well as global cortisol indices (area under the curve -AUC- and slope). Analyses were conducted controlling for age and sex.

Results The ADHD group showed significantly poorer performance across all executive function measures compared to controls. Cortisol levels were significantly lower in the ADHD group at T1 and T2, with a similar trend at T3. Global cortisol indices revealed reduced hypothalamic–pituitary–adrenal axis activation in the ADHD group, reflected by lower AUC values and less negative cortisol slopes. Significant group-by-cortisol slope interactions indicated differential associations between physiological stress regulation and executive performance across groups. Conclusions Children and adolescents with ADHD exhibit a distinct profile of executive dysfunction accompanied by altered physiological stress regulation. These findings highlight the relevance of stress-related biological mechanisms in understanding cognitive functioning in ADHD.