5-HT₂ Receptor Distribution Shown by [¹⁸F] Setoperone PET in High-Functioning Autistic Adults

The serotonergic system is implicated in disordered emotional behavior. Autism is characterized by impaired processing of emotional information. The serotonergic (5-HT) system is also critically involved in brain development, and abnormal brain synthesis of serotonin is observed in autism. Furthermore, whole blood and platelet serotonin have been reported to be elevated in autism. The authors examined the CNS serotonin system in autism in vivo. 5-HT₂ receptors were visualized by PET imaging of [¹⁸F]setoperone-binding in this pilot study of 6 high-functioning autistic adults and 10 matched-control participants. Autism subjects had less thalamic [¹⁸F]setoperone binding than controls, when covaried for age, but no difference reached significance in other areas. A negative relationship between thalamic binding and history of language impairment was also observed. Further studies will be needed to gain a clearer picture of the role of the 5-HT system in autism.