Time‐of‐day effects in arousal: disrupted diurnal cortisol profiles in children with ADHD
Methods: Salivary cortisol was sampled five times a day (awakening, 30 min after awakening, noon, 4 p.m., 8 p.m.) across five consecutive days in 33 children with ADHD (22 with and 11 without oppositional defiant disorder; ODD) and 33 class‐ and sex‐matched controls (aged 6–12). The cortisol awakening response (increase from awakening to 30 min after awakening) and the diurnal cortisol profile (across‐the‐day variations) were compared for ADHD with ODD (ADHD + ODD) and without ODD (ADHD) subgroups and the control group.
Results: The cortisol awakening response was not significantly different between groups. However, longitudinal analyses to evaluate cortisol profiles across the day revealed a significant Group × Time effect (p < .001). More specifically, compared to each other, the ADHD subgroup showed a flatter slope with relative morning hypo‐arousal and evening hyperarousal, whereas the ADHD + ODD subgroup showed a steeper slope with relative morning hyperarousal and evening hypo‐arousal (p < .001).
Conclusions: Findings support time‐related arousal disruptions in children with ADHD associated with the presence or absence of ODD comorbidity. We recommend research on cortisol in larger samples for a better understanding of arousal mechanisms involved in ADHD not only with and without ODD but also with other comorbidities which may have implications for timing of arousal‐based treatments.
Document Type: Research Article
Affiliations: 1: Child and Adolescent Psychiatry Research Unit, Department of Psychiatry and Medical Psychology, Ghent University Hospital, Ghent 2: Department of Experimental-Clinical and Health Psychology, Ghent University, Ghent, Belgium 3: Biostatistics Unit, Ghent University, Ghent
Publication date: July 1, 2012