Event-related potentials elicited during a visual Go-Nogo task in adults with phenylketonuria.

OBJECTIVE: The aim of the present study was to examine the nature of previously reported deficits in sustained attention and response inhibition in adults with the developmental disorder, phenylketonuria (PKU). METHODS: This study used event-related potentials (ERPs) to examine the performance of PKU adults (n=9) and a matched control group (n=9) on a visual Go-Nogo task. RESULTS: Comparison of behavioural measures between the PKU and control groups failed to reach statistical significance, yet analysis of the ERPs showed statistically significant amplitude reductions in the P1 and N1 components elicited following presentation of stimuli, and a reduction in the amplitude of the N2 component elicited following presentation of Nogo stimuli. CONCLUSIONS: These results suggest that adults with PKU, despite being continuously treated from birth, manifest subtle impairments in distinct aspects of information processing including early sensory processing of visually presented information, as well as impairments in inhibitory functions. SIGNIFICANCE: The results contribute to an understanding of the neurophysiological mechanisms that are implicated in PKU and highlight the sensitivity of ERP techniques for the identification of the loci of information processing deficits in clinical groups.