Sustained Attention in Untreated Non-PKU-Hyperphenylalaninemia

Abstract Twenty-four untreated adolescent and adult patients with non-PKU hyperphenylalaninemia (HPA) (serum Phe levels < 600 umol/L) and 24 healthy controls matched for age, sex, and IQ were investigated for simple motor reaction time and sustained attention, which are prolonged in patients with mild or classical phenylketonuria (PKU). Patients with HPA were of normal intelligence and did not differ significantly from healthy controls in their test results. For HPA patients, reaction times and sustained attention were not significantly influenced by serum phenylalanine concentrations. We conclude that dietary treatment is not necessary in patients with non-PKU HPA.