Social-cognitive functioning and social skills in patients with early treated phenylketonuria: a PKU-COBESO study

J Inherit Metab Dis. 2016 May;39(3):355-362. doi: 10.1007/s10545-016-9918-0. Epub 2016 Feb 25.

Abstract

Objective: Early treatment of phenylketonuria (ET-PKU) prevents mental retardation, but many patients still show cognitive and mood problems. In this study, it was investigated whether ET-PKU-patients have specific phenylalanine (Phe-)related problems with respect to social-cognitive functioning and social skills.

Methods: Ninety five PKU-patients (mean age 21.6 ± 10.2 years) and 95 healthy controls (mean age 19.6 ± 8.7 years) were compared on performance of computerized and paper-and-pencil tasks measuring social-cognitive abilities and on parent- and self-reported social skills, using multivariate analyses of variance, and controlling for general cognitive ability (IQ-estimate). Further comparisons were made between patients using tetrahydrobiopterin (BH4, N = 30) and patients not using BH4. Associations with Phe-levels on the day of testing, during childhood, during adolescence and throughout life were examined.

Results: PKU-patients showed poorer social-cognitive functioning and reportedly had poorer social skills than controls (regardless of general cognitive abilities). Quality of social-cognitive functioning was negatively related to recent Phe-levels and Phe-levels between 8 and 12 years for adolescents with PKU. Quality of social skills was negatively related to lifetime phenylalanine levels in adult patients, and specifically to Phe-levels between 0 and 7, and between 8 and 12 years. There were no differences with respect to social outcome measures between the BH4 and non-BH4 groups.

Conclusion: PKU-patients have Phe-related difficulties with social-cognitive functioning and social skills. Problems seem to be more evident among adolescents and adults with PKU. High Phe-levels during childhood and early adolescence seem to be of greater influence than current and recent Phe-levels for these patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Cognition / physiology*
  • Female
  • Humans
  • Male
  • Neuropsychological Tests
  • Phenylalanine / metabolism
  • Phenylketonurias / drug therapy*
  • Phenylketonurias / metabolism
  • Phenylketonurias / physiopathology
  • Phenylketonurias / psychology*
  • Social Skills
  • Young Adult

Substances

  • Phenylalanine