No Difference Between Platelet Serotonin—5-HT 2A Receptors from Children With and Without ADHD

To further investigate the possible function of the serotonergic system in the pathophysiology of attention deficit hyperactivity disorder (ADHD), platelet serotonin 5-HT_2A receptors were characterized for 19 ADHD children and 17 age-matched control subjects. Subjects were evaluated using the Diagnostic Interview for Children and Adolescents (DICA-R-C)–DSM IV and the Children's Depression Inventory. An aggressive subgroup was also determined by the presence of two or more positive aggressive symptoms on either subjects' or parents' reports. Platelets were isolated from venous blood and 5-HT_2A receptor number, and affinity was determined using ¹²⁵I-LSD binding. There was no difference in platelet 5-HT_2A receptor binding characteristics between the two groups. The results from this pilot study suggest a limited function of 5-HT_2A receptors in the pathophysiology of ADHD and extend the findings of other previous negative studies of the peripheral serotonergic system in ADHD.