RESUMO
This study assessed the function of the hypothalamic-pituitary-adrenal (HPA) axis, during response to stress, through the measurement of salivary cortisol in 38 children with attention deficit hyperactivity disorder (ADHD) and its subtypes, who were matched to 38 healthy control subjects. These measures were made at four time intervals: 15 min before exposing the subjects to a stressor - the Continuous Performance Test (CPT) - and 20, 40, and 60 min after such exposure. The baseline cortisol levels were statistically similar in both groups. The mean values of cortisol at the four time intervals were not statistically different between the three subtypes of ADHD (inattentive, hyperactive-impulsive and combined); thus, the ADHD group was treated as a single group. Following the stressor test, the ADHD group had significantly higher levels of salivary cortisol than the control group at time intervals of 20 and 40 min, whereas in this latter group exposure to the CPT did not induce an increase of cortisol. These results suggest that the increased cortisol levels in the ADHD group could be due to the lack of comorbidities. In addition, these patients, when facing a computerized test, might have responded with a motivational pathway with an increase of cortisol.