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

Rianne Jahja*, Francjan J. van Spronsen, Leo M. J. de Sonneville, Jaap J. van der Meere, Annet M. Bosch, Carla E. M. Hollak, Estela Rubio Gozalbo, Martijn C. G. J. Brouwers, Floris C. Hofstede, Maaike C. de Vries, Mirian C. H. Janssen, Ans T. van der Ploeg, Janneke G. Langendonk, Stephan C. J. Huijbregts

*Corresponding author for this work

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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. 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. 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. 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.
Original languageEnglish
Pages (from-to)355-362
JournalJournal of Inherited Metabolic Disease
Issue number3
Publication statusPublished - May 2016

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