[Effect of dietary non-compliance on development in phenylketonuria--studies of 14-year-old patients]
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H Theile1, I Graustein, S Wässer
1Abteilung Humangenetik, Bereiches Medizin, Karl-Marx-Universität Leipzig.
Insights
Early treated phenylketonuria (PKU) patients with good dietary control maintained higher IQs. Diet discontinuation at age 6, even with normal EEG, led to IQ decline, suggesting caution.
Area of Science:
- Neuroscience
- Metabolic Disorders
- Pediatric Neurology
Context:
- Phenylketonuria (PKU) is a genetic disorder requiring early dietary intervention.
- Long-term neurocognitive outcomes in early-treated PKU patients are crucial for management strategies.
- Dietary adherence and timing of treatment discontinuation significantly impact intellectual development.
Purpose:
- To evaluate the long-term impact of dietary control and discontinuation timing on intellectual quotient (IQ) in early-treated PKU children.
- To assess the influence of electroencephalogram (EEG) findings on the decision to discontinue PKU treatment.
- To provide evidence-based recommendations for PKU management regarding diet cessation.
Summary:
- A 14-year study of 25 children with early-treated PKU revealed that good dietary control (phenylalanine levels ≤ 10 mg/dL) correlated with higher IQ scores at ages 6-8, 10, and 14 compared to poor control.
- Despite overall IQ decline in both groups by age 14, discontinuing the diet at age 6 in children with good control and normal EEG post-phenylalanine load resulted in an IQ drop from 100 to 90 by age 10.
- Delayed diet discontinuation due to abnormal EEG at age 6 led to lower initial IQs but stable scores up to age 14, indicating that early diet cessation is not advised even with normal EEG.
Impact:
- Findings challenge the practice of early diet discontinuation at age 6 in PKU management, even with normal EEG results.
- Highlights the critical role of sustained dietary management in preserving cognitive function in PKU patients.
- Informs clinical guidelines for optimizing neurodevelopmental outcomes in individuals with phenylketonuria.
Abstract:
25 children with early treated PKU were studied at the age of 14 years. The IQ was higher at the age of 6-8, 10 and 14 years if the dietary control was good (75% of the control values up to 10 mg/dl) compared to children with poor control. The IQ however decreased up to the age of 14 years in both groups. Discontinuation of the diet in children with a good dietary control at the age of 6 years because of a normal EEG after phenylalanine loading causes a decrease of the IQ from 100 at 6 years to 90 at 10 years. The IQ remains stable thereafter up to 14 years. The IQ ist lower at the age of 7 or 8 years in those children in whom the discontinuation of diet is delayed because of abnormal EEG after phenylalanine loading at the age of 6 years, but remains stable up to the age of 14. According to these results a discontinuation of the diet at the age of 6 years can not be recommended even if the EEG is normal after phenylalanine load.