Information processing deficits in children with early and continuously treated phenylketonuria?

Abstract

Stemerdink BA, van der Molen MW, Kalverboer AF, van der Meere JJ, Hendrikx MMT, Huisman J, van der Schot LWA, Slijper FME. Information processing deficits in children with early and continuously treated phenylketonuria. Acta PEdiatr 1994;(Suppl 407): 106-7. Stockholm. ISSN Thirty-three patients with early and continuously treated classical phenylketonuria (PKU) and 33 controls matched for age, gender, and educational level of both parents, participated in a chronometric study exploring elementary mechanisms of information processing. Subjects performed speeded performance tasks designed to systematically vary the load on perceptual, central, and output-related mechanisms of information processing. A preliminary analysis of the data indicated that the overall performance of patients with early and continuously treated PKU practically matched that of the controls on all three tasks. Although this finding must be interpreted with caution as it is based on only a preliminary analysis of the data, it suggests that PKU patients who are continuously maintained on a well-controlled phenylalanine-restricted diet are not deficient in the elementary mechanisms of processing. Given the mere recent findings indicating that young children with early-treated classical PKU have specific cognitive deficits in the executive function skills, despite relatively strict dietary control, the authors suggest that future studies should focus on these higher-order cognitive processes.While efficient neonatal screening for phenylketonuria (PKU) and early treatment with a diet low i:i phenylalanine (Phe) clearly benefits cognitive development in PKU, many studies have shown that the outcome is not always normal (1). The intelligence tests scores of earlytreated PKU patients are generally within the normal range but often significantly lower than the means of their family members and the mean expected in the general population (2). Additionally, an increased prevalence of behavior problems, learning disabilities, cognitive deficits and attention problems has been noted in these patients (1).The aim of this study was to examine cognitive deficits in patients with early and continuously treated PKU using a chronometric approach to explore elementary information processing mechanisms. The chronometric approach requires a subject to respond as quickly and accurately as pcssible to an imperative stimulus. The dependent measures are mean response time and number of errors. Previous chronometric studies of PKU patients have consistently shown that they perform more slowly and/or less accurately than control groups oli speeded performance tasks (3-1 1).Considering the recent recommendations on stricter dietary control (12), it is important to assess what deficits continue to exist in PKU patients who are treated early and continuously. Patients and methodsThe subjects were 33 PKU patients (mean age 11 years and 8 months; range 7.3-16.8 years) and 33 control children (mean age 11 years and 8 months; range 7.2-16.8 years) matched for age, gender and e...