Plasma cyclic AMP and cyclic GMP in childhood-onset psychoses.

Plasma cyclic AMP is a "second messenger" that may reflect levels of activity of important neurotransmitter receptors. Plasma cyclic AMP was measured in 18 patients with childhood autism, 7 patients with pervasive developmental disorder, and 12 age- and sex-matched healthy controls. Plasma cyclic AMP was significantly elevated by over 100% in both groups of patients with childhood-onset psychoses compared with controls. Plasma cyclic GMP, a nucleotide linked to different receptors, was not elevated, suggesting that the finding may be specific.