Neuropsychological Functioning in Early-Treated Phenylketonuria - A Review

Phenylketonuria (PKU) is an inborn error of metabolism involving a deficiency of the enzyme phenylalanine hydroxylase. This condition results in elevated levels of phenylalanine and low levels of tyrosine. If left untreated, severe neuropathology and neurobehavioral sequelae manifest. The implementation of newborn screening and early dietary treatment has significantly reduced such morbidity. Despite relatively preserved general intellectual functioning, in early-treated PKU individuals subtle cognitive and behavioral deficits are still apparent. This paper provides a review of the evidence for impairment in information processing, executive function, memory and learning, academic achievement and behavior. This paper also reviews the two primary theories proposed to date relating to the underlying mechanisms for the cognitive and behavioral deficits encountered in treated PKU patients, namely prefrontal dysfunction and white matter abnormalities. Although more research is required, the literature to date suggests that early-treated PKU individuals are at risk of subtle neurobehavioral deficits across a range of neuropsychological domains. Thus, PKU Peter Anderson Victorian Infant Brain Studies (VIBeS) Royal Children’s Hospital Flemington Road, Parkville, Vic. 3052 (Australia) Tel. +61 3 9345 4830, Fax +61 3 9345 4840, E-Mail peter.anderson @ mcri.edu.au © 2010 Nestec Ltd., Vevey/S. Karger AG, Basel 0517–8606/10/0682–0078$26.00/0 Accessible online at: www.karger.com/ane D ow nl oa de d by : 54 .1 91 .4 0. 80 9 /1 6/ 20 17 8 :0 9: 12 P M