Symptoms of attention deficit hyperactivity disorder in children are associated with cortisol responses to psychosocial stress but not with daily cortisol levels.

We tested associations of diurnal hypothalamic-pituitary adrenal axis (HPAA) activity and its response to stress with behavioral symptoms of Attention Deficit Hyperactivity Disorder (ADHD) among 272 eight-year-old children. We measured their diurnal salivary cortisol and salivary cortisol responses to the Trier Social Stress Test for Children (TSST-C). Mothers rated their child's behavior with the ADHD-IV Rating Scale and the Child Behavior Checklist (CBCL). There were no significant associations between ADHD symptoms and diurnal cortisol concentrations. The boys with predominantly inattentive symptoms of ADHD (ADHD-I; scores at or above the 90th percentile) had 26% lower mean salivary cortisol levels during the TSST-C than the boys with scores below this cutoff. In the girls with symptoms of ADHD-I, initial salivary cortisol levels prior to the TSST-C were higher and fell more rapidly during and after the TSST-C, which was not seen in the remaining girls (P = 0.007 for interaction 'ADHD-I × sampling time'). Controlling for Oppositional Defiant Disorder/Conduct Disorder and Anxiety Disorder or excluding children with these comorbid problems did not substantially affect these findings. We conclude that the boys and the girls with behavioral symptoms of ADHD-I had reduced HPAA responsiveness to stress, which is also seen in people after traumatic events or with chronic stress. Their diurnal cortisol rhythm was not affected. Thus, ADHD-I may be associated with dysregulation of the HPAA or reduced engagement with stressful stimuli.