Inhibitory control in children with phenylketonuria.

Department of Psychological Sciences, University of Missouri-Columbia, Department of Psychology, Washington University, St. Louis, MO 65211, USA.
Developmental Neuropsychology (Impact Factor: 2.9). 02/2006; 30(3):845-64. DOI:10.1207/s15326942dn3003_5
Source: PubMed

ABSTRACT Past studies have reported impairments in children with early-treated phenylketonuria (PKU) in executive abilities such as strategic processing and working memory. Findings have been inconsistent in terms of the integrity of inhibitory control, another executive ability. This study administered 4 inhibitory tasks (flanker, Stroop, go/no-go, antisaccade) to 26 children with PKU and 25 typically developing control children. Children with PKU performed more poorly than typically developing children on the 2 inhibitory tasks with the strongest experimental manipulations (go/no-go and antisaccade) between control and inhibitory conditions. Findings suggest that the inhibitory deficit associated with PKU is subtle and that inconsistent findings in past studies may be largely due to the insensitivity of experimental manipulations in some tasks.

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    ABSTRACT: AIM: The aim of this study was to assess the effects of iron-deficiency anemia (IDA) in infancy on executive functioning at age 10 years, specifically inhibitory control on the Go/No-Go task. We predicted that children who had IDA in infancy would show poorer inhibitory control. METHOD: We assessed cognitive inhibitory control in 132 Chilean children (mean [SD] age 10y [1mo]): 69 children had IDA in infancy (45 males, 24 females) and 63 comparison children who did not have IDA (26 males, 37 females). Participants performed the Go/No-Go task with event-related potentials. Group differences in behavioral (accuracy, reaction time) and electrophysiological outcomes (N2 and P300 components) were analyzed using repeated-measures analyses of variance. N2 and P300 are interpreted to reflect attention and resource allocation respectively. RESULTS: Relative to comparison participants, children who had IDA in infancy showed slower reaction time (mean [SE], 528.7ms [14.2] vs 485.0ms [15.0], 95% confidence interval [CI] for difference between groups 0.9-86.5); lower accuracy (95.4% [0.5] vs 96.9% [0.6], 95% CI -3.0 to -0.1); longer latency to N2 peak (378.9ms [4.9] vs 356.9ms [5.0], 95% CI 7.5-36.6); and smaller P300 amplitude (4.5μV [0.8] vs 7.6μV [0.9], 95% CI-5.5 to -0.5). INTERPRETATION: IDA in infancy was associated with slower reaction times and poorer inhibitory control 8 to 9 years after iron therapy. These findings are consistent with the long-lasting effects of early IDA on myelination and/or prefrontal-striatal circuits where dopamine is the major neurotransmitter.
    Developmental Medicine & Child Neurology 03/2013; · 2.68 Impact Factor
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    ABSTRACT: Fifty years after the implementation of universal newborn screening programs for phenylketonuria, the first disease identified through newborn screening and considered a success story of newborn screening, a cohort of adults with phenylketonuria treated from birth provides valuable information about effects of long-term treatment for inborn errors of metabolism in general, and phenylketonuria specifically. For phenylketonuria, newborn screening allows early implementation of the phenylalanine-restricted diet, eliminating the severe neurocognitive and neuromotor impairment associated with untreated phenylketonuria. However, executive function impairments and psychiatric problems are frequently reported even for those treated early and continuously with the phenylalanine-restricted diet alone. Moreover, a large percentage of adults with phenylketonuria are reported as lost to follow-up by metabolic clinics. While a group of experts identified by the National Institutes of Health convenes to update treatment guidelines for phenylketonuria, we explore individual patient, social, and economic factors preventing >70% of adult phenylketonuria patients in the United States from accessing treatment. As more conditions are identified through newborn screening, factors affecting access to treatment grow in importance, and we must continue to be vigilant in assessing and addressing factors that affect patient treatment outcomes and not just celebrate amelioration of the most severe manifestations of disease.Genet Med advance online publication 7 March 2013Genetics in Medicine (2013); doi:10.1038/gim.2013.10.
    Genetics in medicine: official journal of the American College of Medical Genetics 03/2013; · 3.92 Impact Factor
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    ABSTRACT: Sapropterin dihydrochloride effectively lowers plasma phenylalanine (Phe) for at least a third of phenylketonuria (PKU) patients, with potential for increased dietary Phe tolerance and decreased medical food requirement. To investigate long-term quality of life (QOL) in patients with phenylketonuria (PKU) who took sapropterin (BH4, Kuvan(R)) for up to one year. 37 PKU patients, ages 10-49 years, were asked to complete a PKU-specific self-report QOL questionnaire (QOLQ) at baseline, 1, 4, 8, and 12 months. Questions were scored on a 5-point Likert scale under 5 sub-sections measuring Impact, Worries, Satisfaction, Support, and General wellbeing in relation to PKU. Responders with a plasma Phe decrease >= 15% after 1 month on sapropterin remained on the drug; Nonresponders ceased sapropterin after the trial month. Responders able to relax medical diet and maintain plasma Phe control were classified as Definitive; Responders unable to relax medical diet were classified as Provisional. All patients were routinely monitored by a registered dietitian. Data was analyzed in SPSS 19.0 using regression techniques. Of 17 Responders, 11 could maintain adequate Phe control on a less restrictive diet. One year mean Impact sub-score trends improved significantly for all sapropterin response groups, with greatest improvement among Definitive Responders (p < 0.0001). Satisfaction sub-scores also improved for Definitive Responders (p = 0.001). Trends for Total QOL score improved significantly over time for both Definitive (p = 0.001) and Provisional Responders (p = 0.028). Improvements in Definitive Responder scores were associated with increased Phe tolerance (Impact: p < 0.0001, Satisfaction: p = 0.022, Total QOL: p = 0.005) and MF adjustment (Satisfaction: p = 0.014, Total QOL: p = 0.026). Other sub-section scores remained steady, unaffected by sapropterin response or diet modification. Increased Phe tolerance and reduced MF requirement in sapropterin Definitive Responders improves QOL perception across one year, specifically for life impact and satisfaction.
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