Increased growth hormone response to sumatriptan challenge in adult autistic disorders

Serotonergic (5-HT) abnormalities have been documented in autism. To assess sensitivity of the 5-HT1d receptor, growth hormone response to the 5-HT1d receptor agonist sumatriptan was studied in adult autistic patients and matched normal controls. In this study, 11 adult patients with autism or Asperger's disorder were compared with nine matched controls. All subjects were randomized to single dose sumatriptan (6 mg SQ) and placebo challenges, separated by a 1-week interval, and growth hormone was measured before and during the challenges. The results showed a highly significant diagnosisxdrugxtime interaction on repeated measure analysis covaried for baseline. This suggests that autistic patients had significantly greater growth hormone response to sumatriptan than normal controls, independent of placebo effects. Therefore, abnormalities in 5-HT regulation in autism may be related to increased sensitivity of the 5-HT1d inhibitory receptor in autism.