The Use of 5-HTP in the Treatment of Down's Syndrome

The clinical use of 5-HTP in the treatment of patients with Down's syndrome was reported by Bazelon and her colleagues in 1967. This approach appeared to offer the hope of improving subnormal development of children with this chromosomal defect. The rationale for the use of 5-HTP is related to its role as the natural biochemical precursor for serotonin (5-hydroxytryptamine). The blood level of this hormone is said to be decreased in Down's syndrome. The present study concerns 26 children with Down's syndrome who were treated with 5-HTP from early infancy until 3 to 4 years of age: 19 completed the course of treatment. DL-5-HTP was given orally with an initial dosage of 0.5 to 1.5 mg/kg/day. The dose was increased stepwise in 1 mg/kg/day increments to a maximum of 5 mg/kg/day. Children were seen by a clinic physician every 1 to 4 months and were assessed by a clinic psychologist every six months. The Gesell Test of Developmental Abilities was used to assess each child's level of development in terms of a total Developmental Quotient (DQ). The psychological findings were analyzed by applying a t test of the difference between independent mean DQs obtained for each age category. The results of this study indicate that long-term systematic use of 5-HTP is not effective in increasing the rate of development of Down's syndrome children.