Effect of l-dopa on visual evoked potentials and neuropsychological tests in adult phenylketonuria patients

Ullrich, Kurt; Weglage, Josef; Pietsch, Michael; Fünders, B; Oberwittler, C.; Eckardstein, H. von; Colombo, J. P.

doi:10.1007/pl00014256

Cited by 19 publications

(12 citation statements)

References 24 publications

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“…However, there is a lack of correlation between these changes and the prolonged VEP latencies measured in adults and children (13). The second hypothesis implies deficient levels of dopamine in the eye and the brain (16). Dopaminergic transmission has been demonstrated in neurones in the retina (24) and the lateral geniculate nuclei (25), and dopamine levels are low in PKU (26).…”

Section: Discussionmentioning

confidence: 99%

“…For instance, the third positive peak (P3) is a late cognitive potential that has a larger amplitude if a stimulus is infrequent and task-relevant (for review, see (8)). ERPs have excellent temporal resolution; changes have been found in the early peaks of scalp-recorded potentials of children and adults with PKU (9)(10)(11)(12)(13)(14)(15)(16). PKU may also affect cognitive P3, as recent studies have shown that dopamine monotherapy in Parkinson's disease causes a reduction in P3 latency (17) for an auditory task.…”

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confidence: 99%

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Visual event‐related potentials in children with phenylketonuria

et al. 2000

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Visual event-related potentials (ERPs) were examined in 16 children (aged 5-14 y) with phenylketonuria (PKU) and 16 age-and sex-matched controls. Lifetime median measures of phenylalanine (Phe) were 230-460 mmol/l. The most recent Phe levels were 56-624 mmol/l. ERPs were recorded whilst the children performed a discrimination task. All stimuli were square wave gratings degree, which appeared for 33 ms. A response to an infrequent grating that differed in orientation or spatial frequency was required. The older children with PKU had a delay in the first peak (P1) of the ERP, and age-related changes in the amplitude of P1. There was attenuation of the second peak across age groups in PKU. There was no evidence of reduced response accuracy or longer reaction times in children with PKU. Latencies of the cognitive P3 were not delayed in PKU. The delayed early peaks are consistent with previous studies that have shown delayed visual evoked potentials in PKU. The lack of differences in reaction time and P3 may be due to relatively good Phe control in children with PKU, or to the simplicity of the task. Suggestions are made for future ERP studies of PKU. phenylalanine, phenylketonuria, reaction time, P3, visual evoked potentials

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Visual event‐related potentials in children with phenylketonuria

et al. 2000

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“…Following these lines of consideration, large doses of tyrosine or L-dopa were expected to have a positive effect. However, later studies with large doses of tyrosine or L-dopa did not show positive results (Lou 1994; Mazzocco et al 1992; Pietz et al 1995; Smith et al 1998; Ullrich et al 1996). …”

Section: Rationale B: Tyrosine And/or Tryptophan Supplementation To Imentioning

confidence: 98%

Large neutral amino acids in the treatment of PKU: from theory to practice

Spronsen

Groot

Hoeksma

et al. 2010

J of Inher Metab Disea

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Notwithstanding the success of the traditional dietary phenylalanine restriction treatment in phenylketonuria (PKU), the use of large neutral amino acid (LNAA) supplementation rather than phenylalanine restriction has been suggested. This treatment modality deserves attention as it might improve cognitive outcome and quality of life in patients with PKU. Following various theories about the pathogenesis of cognitive dysfunction in PKU, LNAA supplementation may have multiple treatment targets: a specific reduction in brain phenylalanine concentrations, a reduction in blood (and consequently brain) phenylalanine concentrations, an increase in brain neurotransmitter concentrations, and an increase in brain essential amino acid concentrations. These treatment targets imply different treatment regimes. This review summarizes the treatment targets and the treatment regimens of LNAA supplementation and discusses the differences in LNAA intake between the classical dietary phenylalanine-restricted diet and several LNAA treatment forms.

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“…Of 15 studies reporting executive function assessments for adults with early-treated PKU and age/gender matched controls without PKU, 13 studies reported mean test scores with variance estimates and were subsequently included in the MA (Antenor-Dorsey et al, 2013;Burgard et al, 1997;Channon et al, 2007;Feldmann, Denecke, Grenzebach, & Weglage, 2005;Griffiths, Paterson, & Harvie, 1995;Luciana, Sullivan, & Nelson, 2001;Moyle, Fox, Bynevelt, Arthur, & Burnett, 2006Pietz et al, 1998Pietz et al, , 1995Ris et al, 1997;Sundermann et al, 2011;Ullrich et al, 1996). The MA effect sizes using Hedges g found significant differences between adults with early-treated PKU and unaffected controls of 0.74 for attention (11 study arms; 252 participants, p < 0.0001), 0.41 for inhibitory control (6 study arms; 119 participants, p = 0.047), and 0.43 for cognitive flexibility (7 study arms; 157 participants, p = 0.006).…”

Section: Meta-analysis: Executive Functionmentioning

confidence: 99%

Systematic Review and Meta-Analysis of Neuropsychiatric Symptoms and Executive Functioning in Adults With Phenylketonuria

Bilder

Noel

Baker

et al. 2016

Developmental Neuropsychology

117

106

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This systematic review and meta-analysis (MA) investigates the impact of elevated blood phenylalanine (Phe) on neuropsychiatric symptoms in adults with phenylketonuria (PKU). The meta-analysis of PKU is challenging because high-quality evidence is lacking due to the limited number of affected individuals and few placebo-controlled, double-blind studies of adults with high and low blood Phe. Neuropsychiatric symptoms associated with PKU exceed general population estimates for inattention, hyperactivity, depression, and anxiety. High Phe is associated with an increased prevalence of neuropsychiatric symptoms and executive functioning deficits whereas low Phe is associated with improved neurological performance. Findings support lifelong maintenance of low blood Phe.

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Effect of l-dopa on visual evoked potentials and neuropsychological tests in adult phenylketonuria patients

Cited by 19 publications

References 24 publications

Visual event‐related potentials in children with phenylketonuria

Visual event‐related potentials in children with phenylketonuria

Large neutral amino acids in the treatment of PKU: from theory to practice

Systematic Review and Meta-Analysis of Neuropsychiatric Symptoms and Executive Functioning in Adults With Phenylketonuria

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