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Preliminary neuropsychological test results
L M de Sonneville1, E Schmidt, U Michel
1Free University Hospital of Amsterdam, Department of Paediatric Neurology, The Netherlands.
Insights
Children with phenylketonuria (PKU) on dietary treatment show sustained attention deficits and slower calculation speeds. Maintaining low phenylalanine (Phe) levels is crucial for cognitive function in PKU patients.
Area of Science:
- Neuroscience
- Pediatrics
- Metabolic Disorders
Background:
- Phenylketonuria (PKU) is a genetic disorder requiring lifelong dietary management.
- High phenylalanine (Phe) levels can negatively impact cognitive development.
- The long-term effects of Phe levels on information processing in treated PKU children are not fully understood.
Purpose of the Study:
- To investigate information processing abilities in children with PKU under dietary treatment.
- To assess the impact of plasma Phe levels on sustained attention and calculation skills.
- To determine the relationship between historical and concurrent Phe levels and cognitive performance.
Main Methods:
- Administered a continuous performance task and a calculation task to 22 PKU children and 20 controls.
- Analyzed performance based on task difficulty and concurrent plasma Phe levels.
- Correlated serum Phe levels (assessed over 6-month periods since birth) with task performance.
Main Results:
- PKU children exhibited a sustained attention deficit compared to controls.
- PKU children were slower in calculation tasks, with performance decreasing as task difficulty increased.
- Higher concurrent Phe levels were associated with significantly worse performance on both tasks.
- Low Phe levels in PKU children led to performance comparable to controls.
- Phe levels measured over the 2 years prior to testing were stronger predictors of sustained attention than concurrent levels.
Conclusions:
- Well-controlled dietary restrictions are vital for optimal cognitive function in PKU.
- Chronic exposure to elevated Phe levels may have lasting effects on attention mechanisms.
- Early and consistent dietary management is essential to mitigate cognitive deficits in PKU.
Abstract:
A series of information processing tasks was administered to 22 PKU children aged 8.5 years who had been under dietary treatment since birth as well as to 20 controls of the same age. This contribution presents the results of two tasks from this series: a continuous performance task and a calculation task. The continuous performance task revealed a sustained attention deficit in the PKU group. In the calculation task the PKU children were slower than the controls and this difference increased with task difficulty. When the PKU sample was divided in two groups (above and below the median value of the concurrent plasma Phe level), the high Phe level group performed much worse in comparison to the low Phe level group. The latter group actually matched performance level of the controls. This could be observed for both tasks. The serum Phe level, assessed since birth over 6 month periods, correlated highly with task performance. As regards sustained attention, the Phe level measured during the 2 years preceeding test administration appeared to be an even better predictor for task performance than the concurrent Phe level, a finding which seems to underline the chronic effect of Phe on basic attention mechanisms. The results so far seem to stress the value of well-controlled dietary restrictions.