Cerebrospinal fluid biopterin and biogenic amine metabolites during oral R-THBP therapy for infantile autism.

Treatment with 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (R-THBP) has been suggested to improve autistic behavior. Cerebrospinal fluid (CSF) levels of total biopterin, oxidized and reduced forms of biopterin, homovanillic acid, and 5-hydroxyindoleacetic acid were measured in 14 autistic children and 18 controls to clarify the mechanism of action of R-THBP. The 14 autistic children received R-THBP orally at 1 mg/kg per day; 7 children showed clinical improvement (responders) and the other 7 patients did not (nonresponders). There were no significant differences between responders, nonresponders, and controls in the CSF levels of the metabolites before R-THBP administration. When lumbar puncture was repeated in 6 autistic children in the 24th week of R-THBP therapy, there was no significant change in the CSF levels of any metabolites.