Social behaviour and task orientation in early-treated PKU.

In the context of the Dutch Collaborative Study on the Psychological Development of Children, early treated for Phenylketonuria (PKU), data were obtained on children's behaviour as perceived by parents (n = 53) and teachers (n = 57), using standardized behavioural questionnaires. Results are compared with a group representative of Dutch school-aged children (n = 1381) with a matched control group (n = 38), and with a group, to be considered as "Attention Deficit Hyperactivity Disorder" (ADHD, n = 38). Especially the clusters "negative task orientation" and "extraversion" distinguish between PKU children and controls. In parents' descriptions as well as in teachers' descriptions PKU children score higher in both clusters. Intriguing differences are found between PKU and ADHD. In parents' but not in teachers' descriptions PKU children show signs of negative task orientation almost to a similar degree as children with ADHD, but not of the signs of "negative social behaviour", characteristic for ADHD children. Data are discussed in terms of the effectiveness of early treatment and guidance.