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A neuropsychological profile of off-diet adults with phenylketonuria

J J Moyle1, A M Fox, M Bynevelt

  • 1School of Psychology, The University of Western Australia, Perth, WA, Australia. jmoyle@student.uwa.edu.au

Journal of Clinical and Experimental Neuropsychology
|May 15, 2007
PubMed

Insights

Phenylketonuria (PKU) patients on a low-phenylalanine diet show reduced information-processing speed. Neuropsychological testing revealed deficits in perceptual organization and processing speed, even with early treatment.

Area of Science:

  • Neuroscience
  • Metabolic Disorders
  • Cognitive Psychology

Background:

  • Phenylketonuria (PKU) is a metabolic disorder typically managed with a low-phenylalanine diet from early life.
  • While early dietary intervention prevents severe global cognitive impairment, some individuals with PKU still exhibit cognitive and neurophysiological abnormalities.

Purpose of the Study:

  • To investigate cognitive and neurophysiological profiles in early-treated adults with PKU who are currently off-diet.
  • To identify specific cognitive deficits in PKU patients compared to control groups.

Main Methods:

  • Neuropsychological testing was administered to early-treated PKU patients attending an adult PKU clinic and a control group.
  • Key assessments included the Wechsler Adult Intelligence Scale Third Edition (WAIS-III) and the Trail Making Test Part A.

Main Results:

  • PKU patients demonstrated a significant reduction in the Perceptual Organization Index (POI) and Processing Speed Index (PSI) from the WAIS-III compared to controls.
  • Performance on the Trail Making Test Part A was also reduced in the PKU group.
  • These findings suggest a specific pattern of cognitive impairment related to information processing speed.

Conclusions:

  • Early dietary treatment for PKU effectively prevents global cognitive impairment but does not fully eliminate cognitive deficits.
  • Adults with PKU, even when treated early, may experience reduced information-processing speed.
  • Further research is needed to understand the long-term neurophysiological consequences and potential interventions for cognitive abnormalities in PKU.

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