Agreement between the Amsterdam Neuropsychological Tasks and the Cambridge Neuropsychological Test Automated Battery in the assessment of PKU patients and healthy controls.

BACKGROUND

Several neuropsychological testing batteries have been used to assess and monitor neurocognitive functioning in healthy individuals and patients. Two of these test batteries, the Amsterdam Neuropsychological Tasks (ANT) and the Cambridge Neuropsychological Automated Test Battery (CANTAB), have indicated impairments in early- and continuously treated phenylketonuria (PKU) patients. However, the tasks of these batteries have never been cross-validated. This study aims to establish the comparability of the two test batteries in the assessment and monitoring of PKU patients and healthy controls.

METHODS

22 PKU patients and 19 controls of various ages (7-67 years old) were tested twice, once using tasks from the ANT and once using tasks from the CANTAB. Tasks of the two batteries were matched based on the neurocognitive functions they (were deemed to) assess, including motor skills, emotion recognition, sustained attention and executive functions (working memory, inhibitory control, and cognitive flexibility). Correlation matrices were used to assess the specificity of the correlations between tasks assigned to similar skills, versus non-related tasks.

RESULTS

Correlations between matched tasks from the ANT and CANTAB ranged from moderate to strong (range ρ: 0.50-0.84, P < 0.001), with strong correlations (ρ > 0.70) for emotion recognition, cognitive flexibility and sustained attention. These correlations remained significant after correcting for age. The strongest correlations were generally found between tasks assigned to require similar skills a-priori, validating the matching between tasks.

CONCLUSION

Overall, there was a good level of agreement between ANT and CANTAB tasks, especially in emotion recognition, sustained attention and the broad construct of executive functioning. These results suggest that a number of ANT and CANTAB tasks assessing the same functions may be used and interpreted interchangeably, which would support a better integration of neuropsychological research in PKU.