The present study investigates the hypothesis of a specific executive function deficit in children with Phenilketonuria (PKU) whose Phenilalanine level is between 360 and 600 mmol/l. Participants were 21 early and continuously treated 9-month-old children with PKU and 18 9-month-old controls. The children with PKU were divided into two groups on the basis of their mean phenilalanine level prior to the study: the group of children whose level was between 120 and 360 mmol/l, and the group of children whose level was between 360 and 600 mmol/l. Although the three groups did not differ with regard to performance on a test of global mental development, the PKU children with high phenilalanine performed significantly worse than both the low phenilalanine PKU children and the control children on a task that assesses executive functioning.
PKU; executive functionining; plasm phenilalanine level
