Behavioural effects of phenylalanine-free amino acid tablet supplementation in intellectually disabled adults with untreated phenylketonuria

Kalkanoglu H., Ahring K., Sertkaya D., Moller L., Romstad A., Mikkelsen I., ...More

ACTA PAEDIATRICA, vol.94, no.9, pp.1218-1222, 2005 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 94 Issue: 9
  • Publication Date: 2005
  • Doi Number: 10.1080/08035250510029488
  • Journal Name: ACTA PAEDIATRICA
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1218-1222
  • Keywords: untreated PKU, behaviour, amino acid tablets, diet supplementation, RESTRICTED DIET, UNITED-STATES, ISOLEUCINE, MUTATIONS, THERAPY, LEUCINE, VALINE
  • Hacettepe University Affiliated: Yes


Aim: To evaluate the effects of phenylalanine ( Phe)-free essential amino acid ( AA) tablets enriched in tyrosine and tryptophan on the performance of intellectually disabled adult patients with untreated phenylketonuria (PKU). Methods: Phe-free AA tablets and placebo tablets were administered to 19 untreated PKU subjects on a normal diet for 6 mo in a prospective double-blinded crossover study. The adaptive behaviour of the patients was tested prior to the study and at 6 and 12 mo after the start, using a simplified version of the Vineland Adaptive Behaviour Scale. For each sub-domain, the patients were rated either "0" ( for poor performance) or "1" ( for good performance). Neurological signs and symptoms and specific behavioural characteristics were recorded monthly by caretakers. Every 6 mo, neurological examination of the patients was performed, and the caretakers were interviewed. The statistical significance of the results was tested by means of the Fisher's exact and Wilcoxon tests. Results: The most significant changes were an improved concentration and the development of a meaningful smile, which were observed in 44% and 43% of the patients on AA tablet treatment, respectively, but not patients on placebo. Other important but less significant changes included increased awareness of external stimuli (63%) and less self-injury (43%), and 40% were smiling and laughing occasionally. The mean overall rating increased from an initial value of 6.3 to 10.1 in patients when on AA tablet treatment (p = 0.002), and to 7.0 in patients when on placebo (p = 0.068). The difference between active AA treatment and placebo was statistically significant (p = 0.027).