Blood cortisol leves of patients with attention deficit/hyperactivity disorder and effects of methylphenidate administration on cortisol levels

Objectives: The aim of this study is to compare cortisol levels of ADHD subjects and healthy controls, and we investigated whether methylphenidate treatment response was predicted by cortisol levels. Material and Methods: A structured clinical interview, Kiddie Schedule for Affective Disorders and Schizophrenia for Shool Aged Children-Present/Lifetime Version was use to determine psychiatric diagnoses. Eighty-nine children with ADHD and 58 healthy controls were recruited to the study. Blood samples were obtained for all participants to determine morning cortisol levels at baseline, and 1st, 3rd, 6th months of methylphenidate treatment. Psychometric tests included Conners Parent/Teacher Rating Scales-Revised/Long forms, Stroop-TBAG form, Clinic Global Impression-Severity Scale that were collected at each visit. Results: DEHB cases with reduced baseline cortisol levels were more frequent in DEHB-Combined type than those in DEHB-Inattention type. Children with ADHD shown a changes in cortisol levels at the end of 6-months of methylphenidate treatment as compared to baseline, although of limited significance. However, the similar results were not seen in control group. There were significant increase from baseline to 6th months of treatment in plasma cortisol levels among boys with ADHD, and cases with combined type, whereas no changes were observed among girls with ADHD, also among control boys and girls, and ADHD cases with predominantly inattentive type. We observed a significant increase of cortisol levels at the 3rd, 6th months of treatment in the ADHD patients with symptoms of moderate levels, but not in those with mild or severe ADHD symptoms. Conclusions: Cortisol levels may predict methylphenidate treatment responses, especially in boys with moderate levels of ADH symptoms, and with combined type. It is a need to plan further studies including other medical agents, and also stress and sex hormones. Results from future studies can be useful to understand pathophysiology of ADHD and to predict treatment responses.