Randomised controlled trial of tyrosine supplementation on neuropsychological performance in phenylketonuria.

Abstract

OBJECTIVE:

To test the efficacy of tyrosine supplementation, as an adjunct to dietary treatment, on neuropsychological test performance in individuals with phenylketonuria.

DESIGN:

A randomised controlled trial of tyrosine supplementation using a double blind crossover procedure with three four week phases.

SETTING:

The Hospital for Sick Children, Toronto.

PARTICIPANTS:

21 individuals with phenylketonuria (ages 6 to 28 years, mean 11.3).

INTERVENTION:

Participants were given 100 mg/kg body weight/d of L-tyrosine or L-alanine (placebo).

RESULTS:

At baseline, performance on several of the neuropsychological test measures was correlated with tyrosine levels. Dietary supplements of tyrosine increased plasma tyrosine concentrations; however, no change in test performance was found across the tyrosine and placebo phases of the study.

CONCLUSIONS:

Tyrosine supplementation of this type does not appear to alter neuropsychological performance in individuals with phenylketonuria.

• Authors: M L Smith, W B Hanley, J T Clarke, P Klim, W Schoonheyt, V Austin, D C Lehotay
• Journal: Archives of disease in childhood (Arch Dis Child) Vol. 78 Issue 2 Pg. 116-21 (Feb 1998) ISSN: 1468-2044 [Electronic] England
• PMID: 9579151 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial)

Chemical References

• Tyrosine
• Phenylalanine
• Alanine

Topics

• Administration, Oral
• Adolescent
• Adult
• Alanine (administration & dosage)
• Child
• Cross-Over Studies
• Double-Blind Method
• Female
• Humans
• Male
• Neuropsychological Tests
• Phenylalanine (blood)
• Phenylketonurias (blood, diet therapy, psychology)
• Treatment Failure
• Tyrosine (administration & dosage, blood, therapeutic use)