TRANSITORY HYPERPHENYLALANINEMIA IN CHILDREN WITH CONTINUOUSLY TREATED PHENYLKETONURIA

Cognitive and behavioral effects of temporarily challenging the CNS wi th elevated levels of phenylalanine in treated phenylketonuria (PKU) w ere investigated in a triple-blind, cross-over study, A high phenylala nine supplement was given over 3 months to sixteen 10- to 16-year-old early and continuously treated children with classical PKU. We used th e WISC and Rivermead tests to measure cognitive function and the Rutte r Scales to assess disordered behavior. Parents and children guessed a t the condition imposed. The Group x Phase interaction for phenylalani ne level was statistically significant, but this pattern was not mirro red in the psychological test data, and guessing was random, Results s uggest that intellectual ability, memory, and conduct are not affected by medium-term hyperphenylalaninaemia in PKU after 10 or more years o f treatment.