A systematic review of cognitive functioning in early treated adults with phenylketonuria

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Abstract

Background

Even though early dietary management of phenylketonuria (PKU) successfully prevents severe neurological impairments, deficits in cognitive functioning are still observed. These deficits are believed to be the result of elevated levels of phenylalanine throughout life. Research on cognitive functioning in adults with PKU (AwPKU) often focuses on domains shown to be compromised in children with PKU, such as attention and executive functions, whereas other cognitive domains have received less attention. This systematic review aimed to provide an overview of cognitive functioning across domains examined in early treated (ET) AwPKU.

Methods

A systematic search was performed in Ovid MEDLINE(R), PsycINFO, Web of Science, Cochrane, Scopus, Embase, ScienceDirect, and PubMed for observational studies on cognitive performance in ET AwPKU.

Results

Twenty-two peer-reviewed publications, reporting on outcomes from 16 studies were reviewed. Collectively, the results most consistently showed deficits in vigilance, working memory and motor skills. Deficits in other cognitive domains were less consistently observed or were understudied. Furthermore, despite reports of several associations between cognitive performance and phenylalanine (Phe) levels throughout life the relationship remains unclear. Inconsistencies in findings across studies could be explained by the highly heterogeneous nature of study samples, resulting in large inter- and intra-variability in Phe levels, as well as the use of a variety of tests across cognitive domains, which differ in sensitivity. The long-term cognitive outcomes of early and continuous management of PKU remain unclear.

Conclusions

To better understand the development of cognitive deficits in ET AwPKU, future research would benefit from 1) (inter)national multicentre-studies; 2) more homogeneous study samples; 3) the inclusion of other nutritional measures that might influence cognitive functioning (e.g. Phe fluctuations, Phe:Tyrosine ratio and micronutrients such as vitamin B12); and 4) careful selection of appropriate cognitive tests.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0893-4) contains supplementary material, which is available to authorized users.

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Most cited references 76

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Article: not found

Using Effect Size-or Why the P Value Is Not Enough.

Gail M Sullivan, Richard Feinn (2012)

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Record: found
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Article: not found

Reviewing studies with diverse designs: the development and evaluation of a new tool.

Reema Sirriyeh, Rebecca Lawton, Peter Gardner … (2012)

RATIONALE, AIMS & OBJECTIVE: Tools for the assessment of the quality of research studies tend to be specific to a particular research design (e.g. randomized controlled trials, or qualitative interviews). This makes it difficult to assess the quality of a body of research that addresses the same or a similar research question but using different approaches. The aim of this paper is to describe the development and preliminary evaluation of a quality assessment tool that can be applied to a methodologically diverse set of research articles. The 16-item quality assessment tool (QATSDD) was assessed to determine its reliability and validity when used by health services researchers in the disciplines of psychology, sociology and nursing. Qualitative feedback was also gathered from mixed-methods health researchers regarding the comprehension, content, perceived value and usability of the tool. Reference to existing widely used quality assessment tools and experts in systematic review confirmed that the components of the tool represented the construct of 'good research technique' being assessed. Face validity was subsequently established through feedback from a sample of nine health researchers. Inter-rater reliability was established through substantial agreement between three reviewers when applying the tool to a set of three research papers (κ = 71.5%), and good to substantial agreement between their scores at time 1 and after a 6-week interval at time 2 confirmed test-retest reliability. The QATSDD shows good reliability and validity for use in the quality assessment of a diversity of studies, and may be an extremely useful tool for reviewers to standardize and increase the rigour of their assessments in reviews of the published papers which include qualitative and quantitative work. © 2011 Blackwell Publishing Ltd.

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Is Open Access

The complete European guidelines on phenylketonuria: diagnosis and treatment

A. van Wegberg, A. MacDonald, K. Ahring … (2017)

Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine metabolism caused by deficiency in the enzyme phenylalanine hydroxylase that converts phenylalanine into tyrosine. If left untreated, PKU results in increased phenylalanine concentrations in blood and brain, which cause severe intellectual disability, epilepsy and behavioural problems. PKU management differs widely across Europe and therefore these guidelines have been developed aiming to optimize and standardize PKU care. Professionals from 10 different European countries developed the guidelines according to the AGREE (Appraisal of Guidelines for Research and Evaluation) method. Literature search, critical appraisal and evidence grading were conducted according to the SIGN (Scottish Intercollegiate Guidelines Network) method. The Delphi-method was used when there was no or little evidence available. External consultants reviewed the guidelines. Using these methods 70 statements were formulated based on the highest quality evidence available. The level of evidence of most recommendations is C or D. Although study designs and patient numbers are sub-optimal, many statements are convincing, important and relevant. In addition, knowledge gaps are identified which require further research in order to direct better care for the future.

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Author and article information

Contributors

Denise Leonne Hofman:

ORCID: http://orcid.org/0000-0003-0994-3630

psdlh@leeds.ac.uk

Claire Louise Champ: c.l.champ@leeds.ac.uk

Clare Louise Lawton: c.l.lawton@leeds.ac.uk

Mick Henderson: mick.henderson@nhs.net

Louise Dye: l.dye@leeds.ac.uk

Journal

Journal ID (nlm-ta): Orphanet J Rare Dis

Journal ID (iso-abbrev): Orphanet J Rare Dis

Title: Orphanet Journal of Rare Diseases

Publisher: BioMed Central (London )

ISSN (Electronic): 1750-1172

Publication date (Electronic): 30 August 2018

Publication date PMC-release: 30 August 2018

Publication date Collection: 2018

Volume: 13

Electronic Location Identifier: 150

Affiliations

[1 ]ISNI 0000 0004 1936 8403, GRID grid.9909.9, School of Psychology, , University of Leeds, ; Leeds, LS2 9JT UK

[2 ]GRID grid.443984.6, Biochemical Genetics, Specialist Laboratory Medicine, , St James’s University Hospital, ; Block 46, Leeds, LS9 7TF UK

Author information

Denise Leonne Hofman http://orcid.org/0000-0003-0994-3630

Article

Publisher ID: 893

DOI: 10.1186/s13023-018-0893-4

PMC ID: 6117942

PubMed ID: 30165883

SO-VID: aa7ff32d-2d9d-4e85-8ed5-96c4a9459ca4

License:

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

History

Date received : 30 July 2018

Date accepted : 16 August 2018

Funding

Funded by: Medical Research Council (UK)

Award ID: 1495645

Award Recipient : Denise Leonne Hofman

Custom metadata

ScienceOpen disciplines: Infectious disease & Microbiology

Keywords: phenylketonuria,cognitive function,attention,processing speed,executive function,motor skills

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ScienceOpen disciplines: Infectious disease & Microbiology

Keywords: phenylketonuria, cognitive function, attention, processing speed, executive function, motor skills

A systematic review of cognitive functioning in early treated adults with phenylketonuria

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Annual Reviews: Coronavirus Research

Most cited references 76

Using Effect Size-or Why the P Value Is Not Enough.

Reviewing studies with diverse designs: the development and evaluation of a new tool.

The complete European guidelines on phenylketonuria: diagnosis and treatment

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