Cortical serotonin 5-HT2A receptor binding and social communication in adults with Asperger's syndrome: an in vivo SPECT study.

OBJECTIVE

The cause of autistic spectrum disorder (i.e., autism and Asperger's syndrome) is unknown. The serotonergic (5-HT) system may be especially implicated. However, cortical 5-HT2A receptor density in adults with the disorder has not been examined, to the authors' knowledge.

METHOD: The authors investigated cortical 5-HT2A receptor binding in eight adults with Asperger's syndrome and in 10 healthy comparison subjects with single photon emission computed tomography and the selective 5-HT2A receptor ligand 123I iodinated 4-amino-N-[1-[3-(4-fluorophenoxy)propyl]-4-methyl-4-piperidinyl]-5-iodo-2-methoxybenzamide (123I-5-I-R91150).

RESULTS

People with Asperger's syndrome had a significant reduction in cortical 5-HT2A receptor binding in the total, anterior, and posterior cingulate; bilaterally in the frontal and superior temporal lobes; and in the left parietal lobe. Also, reduced receptor binding was significantly related to abnormal social communication.

CONCLUSIONS

The authors' findings suggest that adults with Asperger's syndrome have abnormalities in cortical 5-HT2A receptor density and that this deficit may underlie some clinical symptoms.