Behavior in children with Prader-Willi syndrome before and during growth hormone treatment: a randomized controlled trial and 8-year longitudinal study.

Information on behavior of children with Prader-Willi syndrome (PWS) and the effect of growth hormone (GH) treatment is scarce. Parents report less problem behavior during GH treatment. Forty-two pre-pubertal children, aged 3.5-14 years were studied in a randomized controlled GH trial (RCT) during 2 years, followed by a longitudinal study during 8 years of GH treatment. Behavior was measured annually by the Developmental Behavior Checklist for children with intellectual disability (DBC) and a Dutch questionnaire to evaluate social behavioral problems in children, the Children's Social Behavior Questionnaire (CSBQ). Problem behavior measured by the DBC in children with PWS was similar compared to peers with comparable intellectual disability. Scores on 'Social disabilities' subscale were however significantly higher compared to the DBC total score (p < 0.01). A lower IQ was associated with more self-absorbed behavior, more communication problems and more problem behavior in general. Problem behavior measured by the CSBQ was similar compared to peers with a comparable intellectual disability, but children with PWS scored significantly higher on the 'Not tuned', 'Understanding', and 'Stereotyped' subscales than the CSBQ total score (p < 0.05 for all subscales and p = 0.001 for the 'Not tuned'-subscale). There were no significant effects of GH treatment during the RCT and 8 years of GH treatment. Children with PWS showed similar problem behavior as a reference population with a comparable intellectual disability. Social problems were the most pronounced within-problem behavior in PWS. In contrast to our expectations and parents reports, our study shows no improvement but also no deterioration of behavioral problems in children with PWS during long-term GH treatment.