Early psychosocial adversity and cortisol levels in children with attention-deficit/hyperactivity disorder.

Previous studies suggest a different regulation of the hypothalamus-pituitary-adrenal axis (HPA-axis) with lower diurnal cortisol levels, especially in the morning, in children with attention-deficit/hyperactivity disorder (ADHD) compared with controls. Since exposure to foetal and childhood psychosocial adversity has been associated with both ADHD and HPA-axis functioning, such exposures may explain these low cortisol levels in ADHD via early programming of the HPA-axis. Thus, our main aim was to retrospectively study foetal and early childhood exposures to psychosocial adversity in children with ADHD and to relate these exposures to cortisol levels. Saliva samples were collected during a regular weekday in children, 6-17 years old, with clinically confirmed ADHD (n = 197) and non-affected comparisons (n = 221) for radioimmunoassay analysis of cortisol. Parental rating scales were used for categorising subtypes of ADHD and degree of exposure to adversity. Children with ADHD had more reports of at least one rated foetal adversity (p = 0.041) and childhood adversity (p < 0.001) than comparisons. The association between low morning cortisol levels and ADHD-symptoms remained when analyses were adjusted for adversities, age, sex, sampling time and symptoms of oppositional defiant disorder. No relation was found between exposures to foetal/childhood adversity and cortisol levels except for a positive relation between childhood adversity and cortisol morning increase in children with ADHD. The hypothesis that early adversity may influence the HPA-axis, leading to lower cortisol levels in children with ADHD, was not supported by our findings.