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Visual event-related potentials in children with phenylketonuria
R M Henderson1, D L McCulloch, A M Herbert
1Department of Vision Sciences, Glasgow Caledonian University, Scotland. rmhe@gcal.ac.uk
Insights
Children with phenylketonuria (PKU) show delayed early visual event-related potentials (ERPs), particularly the P1 peak, indicating visual processing differences. However, cognitive P3 responses and task performance remained unaffected, suggesting potential benefits from phenylalanine management.
Area of Science:
- Neuroscience
- Developmental Psychology
- Metabolic Disorders
Background:
- Phenylketonuria (PKU) is a metabolic disorder affecting phenylalanine levels.
- Visual processing differences have been suggested in individuals with PKU.
- Event-related potentials (ERPs) offer insights into neural processing speed and efficiency.
Purpose of the Study:
- To investigate visual event-related potentials (ERPs) in children with phenylketonuria (PKU).
- To assess the impact of PKU on early visual processing and cognitive responses.
- To correlate ERP findings with phenylalanine (Phe) levels and age in children with PKU.
Main Methods:
- Visual ERPs were recorded from 16 children with PKU (aged 5-14 years) and 16 controls.
- Participants performed a visual discrimination task involving square wave gratings.
- Analysis focused on peak latencies and amplitudes of early (P1) and cognitive (P3) ERP components.
Main Results:
- Older children with PKU exhibited delayed P1 peak latency and altered P1 amplitude.
- Attenuation of the second ERP peak was observed across age groups in the PKU cohort.
- No significant differences in response accuracy or reaction times were found between groups.
Conclusions:
- Delayed early visual ERPs in children with PKU align with previous findings of visual evoked potential delays.
- The lack of P3 latency differences may be attributed to effective Phe control or task simplicity.
- Further ERP research is recommended to explore visual processing in PKU.
Abstract:
Visual event-related potentials (ERPs) were examined in 16 children (aged 5-14 y) with phenylketonuria (PKU) and 16 age- and sex-matched controls. Lifetime median measures of phenylalanine (Phe) were 230-460 micromol/l. The most recent Phe levels were 56-624 micromol/l. ERPs were recorded whilst the children performed a discrimination task. All stimuli were square wave gratings degree, which appeared for 33 ms. A response to an infrequent grating that differed in orientation or spatial frequency was required. The older children with PKU had a delay in the first peak (P1) of the ERP, and age-related changes in the amplitude of P1. There was attenuation of the second peak across age groups in PKU. There was no evidence of reduced response accuracy or longer reaction times in children with PKU. Latencies of the cognitive P3 were not delayed in PKU. The delayed early peaks are consistent with previous studies that have shown delayed visual evoked potentials in PKU. The lack of differences in reaction time and P3 may be due to relatively good Phe control in children with PKU, or to the simplicity of the task. Suggestions are made for future ERP studies of PKU.