Routine use of CANTAB system for detection of neuropsychological deficits in patients with PKU

Several studies have reported neuropsychological deficits related to hyper phenylalaninemia in patients with phenylketonuria (PKU). As computerized neuropsychological tests seem to be promising in the detection of such abnormalities, we aimed to assess the usefulness of routine use of CANTAB system in PKU clinic. A group of 49 PKU patients aged >16 years were tested by means of computerized CANTAB tests measuring speed of response, response inhibition, sustained attention, and working memory capacity. The scores achieved by study participants were analyzed with respect to their blood phenylalanine concentrations. Proper dietary control was observed in 22 patients, whereas in the remaining 27 persons, blood phenylalanine concentrations exceeded the recommended range. The results of the tests assessing sustained attention, working memory, and inhibitory control achieved by the non-compliant patients were significantly worse in comparison with patients maintaining proper diet. However, the mean scores achieved by treatment-adherent patients were also worse than expected, what could probably be related to problems with early start of treatment during their infancy. Our results confirmed the presence of specific neuropsychological deficits related to hyperphenylalaninemia in adults and adolescents with PKU. In our opinion, routine use of computerized neuropsychological tests should be recommended in PKU clinics.