Executive function and psychosocial adjustment in children with early treated phenylketonuria: correlation with historical and concurrent phenylalanine levels.
In early-treated PKU kids at UK upper-limit phe levels, executive and behavior scores are normal, so tighter diet may not help cognition.
01Research in Context
What this study did
The team asked: do blood phenylalanine levels predict thinking or behavior problems in early-treated PKU kids?
They tested the children . All had PKU found at birth and steady diet care.
Kids gave blood samples. Parents and teachers filled out behavior forms. Each child took paper-and-pencil and computer thinking tests.
What they found
Current and past phenylalanine levels were not linked to any test score. Executive skills, memory, and mood ratings all looked average.
Even kids whose levels sometimes hit the UK upper limit showed no extra problems.
How this fits with other research
Samyn et al. (2015) also worked with 8-young learners and found that parent questionnaires and lab EF tasks measure different things. P et al. used both kinds of tools, so their null result is unlikely to be a measurement mix-up.
Gilboa et al. (2014) showed that children with the genetic condition NF1 have clear writing and planning deficits. P et al. found no such signature in early-treated PKU, suggesting that steady metabolic control can protect the brain.
Smith et al. (2021) linked fine motor skill to IQ in ADHD. P et al. did not look at motor scores, but both studies remind us to check whether a deficit is specific to the medical label or shared across conditions.
Why it matters
If a PKU child's levels stay near the UK upper target, you can reassure families that extra strict diet cuts may not be needed. Focus teaching time on typical academic or social goals instead of metabolic fear. Still track blood phe, but use the session for skill building, not worry.
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02At a glance
03Original abstract
The issue of what level of phenylalanine (phe) constitutes a safe upper limit for the therapeutic range in dietary treatment of phenylketonuria (PKU) remains unsettled. It has been proposed that the previous guideline figure of 600 mumol l-1 may result in specific impairment of executive functions such as attention, planning and set maintenance. The executive dysfunction theory was investigated by correlation historical and concurrent phe with executive, non-executive and personality tests in a group of early and continuously treated children, aged 10-13 years, with classical PKU, whose average phe levels of 355 mumol l-1 (SD = +/-144) for the pre-school period and 480 mumol l-1 (SD +/-193) for the primary school period corresponded to the upper limits presently recommended in the UK of 360 and 480 mumol l-1 for these age ranges. No clear associations were found between historical or concurrent phe levels and any of the neuropsychological or personality measures, thereby weakening the case for the emergence of executive deficits, at least when average phe levels remain close to the upper limits now considered safe. Furthermore no significant differences were found on psychological variables where comparison with population norms was possible.
Journal of intellectual disability research : JIDR, 1997 · doi:10.1111/j.1365-2788.1997.tb00715.x