Deficits in selective and sustained attention processes in early treated children with phenylketonuria — result of impaired frontal lobe functions?

Twenty normally intelligent children with early treated phenylketonuria (PKU) (IQ: mean=101.4, SD=10.0; age: mean=10 years 11 months, SD=1.3 years) and 20 healthy controls, matched for age, sex and IQ, were assessed for their selective (Stroop Task) and sustained attention (Test-d-2). Using positron emission tomography an activation of the frontal lobe during the Stroop task had previously been demonstrated. In addition to the Stroop Task and the Test-d-2, a short-term memory test as a “non-frontal-lobe-function-task” was administered to all subjects. Group comparisons demonstrated that PKU children had specific deficits in selective and sustained attention, which were significantly correlated with the concurrent serum phenylalanine concentration.