University of Groningen Social-cognitive functioning and social skills in patients with early treated phenylketonuria

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 parentand 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 Phelevels 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 socialcognitive functioning was negatively related to recent Phelevels 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 outcomemeasures 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. Abbreviations ANT Amsterdam Neuropsychological Tasks EF Executive function(ing) FPT Faux-Pas Recognition Test FR Face Recognition IFE Identification of Facial Emotions Phe Phenylalanine PKU Phenylketonuria PKU-COBESO Phenylketonuria COgnition, BEhavior, SOcial functioning study Communicated by: Alberto B Burlina * Rianne Jahja jahjar@umcg.nl 1 University of Groningen, University Medical Center Groningen, Beatrix Children’s Hospital, Division of Metabolic Diseases CA33, PO Box 30.001, 9700 RB Groningen, The Netherlands 2 Department of Clinical Child and Adolescent Studies & Leiden Institute for Brain and Cognition, Leiden University, Leiden, The Netherlands 3 Department of Developmental and Clinical Neuropsychology, University of Groningen, Groningen, The Netherlands 4 Academic Medical Center, Amsterdam, The Netherlands 5 Laboratory Genetics Metabolic Diseases, University Hospital Maastricht, Maastricht, The Netherlands 6 Wilhelmina Children’s Hospital, University Medical Center Utrecht, Utrecht, The Netherlands 7 University Medical Center St Radboud Nijmegen, Nijmegen, The Netherlands 8 Center for Lysosomal and Metabolic Diseases, Erasmus Medical Center, Rotterdam, The Netherlands J Inherit Metab Dis (2016) 39:355–362 DOI 10.1007/s10545-016-9918-0