Screening for cognitive and social-emotional problems in individuals with PKU: tools for use in the metabolic clinic

Role of Psychologists in Pediatric Metabolic Disorders

Metabolic disorders or inborn errors of metabolism (IEMs) can have a wide range of neurodevelopmental and behavioral presentations. These can vary with age and/or management or stressors from common childhood/intercurrent illnesses/procedures/interventions. Collaborative care models such as multidisciplinary metabolic clinics or colocated models with behavioral health clinics and metabolic clinics in the same location can be valuable resources in improving long-term outcomes in patients with IEM. Psychologists' expertise using behavioral interventions, screening, or adaptive/cognitive measures can help with diagnosis, treatment adherence, school performance, family support, community resources, transition to adolescence and young adulthood using health belief concepts to improve outcomes.

Everyday Life, Dietary Practices, and Health Conditions of Adult PKU Patients: A Multicenter, Cross-Sectional Study

BACKGROUND

Only few data on dietary management of adult phenylketonuria (PKU) patients are published.

OBJECTIVES

This study aimed to assess living situation, dietary practices, and health conditions of early-treated adult PKU patients.

METHODS

A total of 183 early-treated PKU patients ≥18 years from 8 German metabolic centers received access to an online survey, containing 91 questions on sociodemographic data, dietary habits, and health conditions.

RESULTS

144/183 patients (66% females) completed the questionnaire. Compared with German population, the proportion of single-person households was higher (22 vs. 47%), the rate of childbirth was lower (1.34 vs. 0.4%), but educational and professional status did not differ. 82% of the patients adhered to a low-protein diet, 45% consumed modified low-protein food almost daily, and 84% took amino acid mixtures regularly. 48% of the patients never interrupted diet, and 14% stopped diet permanently. 69% of the patients reported to feel better with diet, and 91% considered their quality of life at least as good. The prevalence of depressive symptoms was high (29%) and correlated significantly to phenylalanine blood concentrations (p = 0.046). However, depressive symptoms were only mild in the majority of patients.

CONCLUSION

This group of early-treated adult German PKU patients is socially well integrated, reveals a surprisingly high adherence to diet and amino acid intake, and considers the restrictions of diet to their daily life as low.

The role of integrated behavioral health in caring for patients with metabolic disorders

This review of integrated behavioral health (IBH) provides a background on IBH models, and the benefits of IBH in pediatric practice with an emphasis on how IBH specialists can collaborate with families and clinicians. An overview of intellectual disability (ID) and psychiatric disorders focused on disorders of inborn errors of metabolism (IEM) highlights issues in assessment and monitoring of these patients with implications for clinical practice and the role of IBH in caring for patients with IEM disorders.

Executive function in adolescents with PKU and their siblings: Associations with biochemistry

Previous research shows consistent and marked executive function impairment in children with early and continuously treated phenylketonuria. This between groups analysis (phenylketonuria group vs sibling controls) found no significant differences in executive function (although adolescents with phenylketonuria performed slightly worse than their siblings). Biochemical relationships with executive function were confined to long-term measures of high phenylalanine:tyrosine ratio exposure, as well as tyrosine exposure independent of phenylalanine. This study suggests that early and continuously treated PKU results in non-significant EF differences (compared to siblings), although the influence of long-term exposure to poorer metabolic control is still evident.

Evaluation of Neuropsychiatric Function in Phenylketonuria: Psychometric Properties of the ADHD Rating Scale-IV and Adult ADHD Self-Report Scale Inattention Subscale in Phenylketonuria

BACKGROUND

Previous qualitative research among adults and parents of children with phenylketonuria (PKU) has identified inattention as an important psychiatric aspect of this condition. The parent-reported ADHD Rating Scale-IV (ADHD RS-IV) and the Adult ADHD Self-Report Scale (ASRS) have been validated for measuring inattention symptoms in persons with attention-deficit/hyperactivity disorder (ADHD); however, their psychometric attributes for measuring PKU-related inattention have not been established.

OBJECTIVE

The primary objective of this investigation was to demonstrate the reliability, validity, and responsiveness of the ADHD RS-IV and ASRS inattention symptoms subscales in a randomized controlled trial of patients with PKU aged 8 years or older.

METHODS

A post hoc analysis investigated the psychometric properties (Rasch model fit, reliability, construct validity, and responsiveness) of the ADHD RS-IV and ASRS inattention subscales using data from a phase 3b, double-blind, placebo-controlled clinical trial in those with PKU aged 8 years or older.

RESULTS

The Rasch results revealed good model fit, and reliability analyses revealed strong internal consistency reliability (α ≥ 0.87) and reproducibility (intraclass correlation coefficient ≥ 0.87) for both measures. Both inattention measures demonstrated the ability to discriminate between known groups (P < 0.001) created by the Clinical Global Impression-Severity scale. Correlations between the ADHD RS-IV and the ASRS with the Clinical Global Impression-Severity scale and the age-appropriate Behavior Rating Inventory of Executive Function Working Memory subscale were consistently moderate to strong (r ≥ 0.56). Similarly, results of the change score correlations were of moderate magnitude (r ≥ 0.43) for both measures when compared with changes over time in Behavior Rating Inventory of Executive Function Working Memory subscales.

CONCLUSIONS

These findings of reliability, validity, and responsiveness of both the ADHD RS-IV and the ASRS inattention scales, in addition to content validation results, support their use for the assessment of inattention symptoms among persons with PKU aged 8 years or older in both clinical and research settings.

Executive functioning of 4 children with hyperphenylalaninemia from childhood to adolescence

Hyperphenylalaninemia is a variant of phenylketonuria, and debate remains as to what, if any, active management of this condition is required to preserve cognitive function and psychological well-being. This study is the first to examine longitudinally the executive function (EF) in adolescents with hyperphenylalaninemia. Two sibling pairs with mild hyperphenylalaninemia underwent neuropsychological examination in early childhood and again in adolescence using EF tests that were highly sensitive to phenylalanine exposure. By early adolescence, none of the 4 children demonstrated EF impairment. The children demonstrated a typical developmental trajectory of EF from childhood to adolescence, given phenylalanine exposure consistent with their condition.

Is BRIEF a useful instrument in day to day care of patients with phenylketonuria?

OBJECTIVES

Despite early and continuous treatment many patients with phenylketonuria (PKU) still experience neurocognitive problems. Most problems have been observed in the domain of executive functioning (EF). For regular monitoring of EF, the use of the Behavior Rating Inventory of Executive Function (BRIEF) has been proposed. The aim of this study was to investigate whether the BRIEF is indeed a useful screening instrument in monitoring of adults with PKU.

STUDY DESIGN

Adult PKU patients (n = 55; mean age 28.3 ± 6.2 years) filled out the BRIEF-A (higher scores=poorer EF) and performed computerized tasks measuring executive functions (inhibition, cognitive flexibility, and working memory). The outcome of the BRIEF-A questionnaire was compared with the neurocognitive outcome as measured by three tasks from the Amsterdam Neuropsychological Tasks (ANT).

RESULTS

Forty-two percent of the PKU patients scored in the borderline/clinical range of the BRIEF-A. Six of the 55 patients (11%) scored >1 SD above the normative mean, mostly on the Metacognition Index. With respect to ANT measurements, patients mainly showed deficits in inhibitory control (34-36%) and cognitive flexibility (31-40%) as compared to the general Dutch population. No significant correlations between the two methods were found, which was confirmed with the Bland-Altman approach where no agreement between the two methods was observed. Only with respect to inhibitory control, patients scored significantly worse on both BRIEF-A and ANT classifications. No other associations between classification according to the BRIEF-A and classifications according to the ANT tasks were found.

CONCLUSIONS

Patients reporting EF problems in daily life are not necessarily those that present with core EF deficits. The results of this study suggest that regular self-administration of the BRIEF-A is not a sufficient way to monitor EF in adult PKU patients.

Assessing Psychological Functioning in Metabolic Disorders: Validation of the Adaptive Behavior Assessment System, Second Edition (ABAS-II), and the Behavior Rating Inventory of Executive Function (BRIEF) for Identification of Individuals at Risk

Long-term follow-up of neuropsychological functioning in metabolic disorders remains difficult due to limited opportunities for comprehensive neuropsychological evaluations. This study examined the validity of using the Adaptive Behavior Assessment System, Second Edition (ABAS-II), and the Behavior Rating Inventory of Executive Function (BRIEF) for assessing developmental status in metabolic disorders and for identifying individuals at risk for cognitive deficits. Results from individuals with urea cycle disorders, phenylketonuria, galactosemia, and fatty acid oxidation disorders were obtained on the ABAS-II and BRIEF and were compared to results obtained from neuropsychological testing performed on the same day. Correlations between scores on the ABAS-II and developmental or IQ tests for individuals with urea cycle disorders ranged from 0.48 to 0.72 and concordance rates for scores greater than a standard deviation below the normative mean ranged from 69 to 89%. Correlations ranged from 0.20 to 0.68 with concordance ranging from 73 to 90% in the other metabolic disorders. For the BRIEF, correlations with other tests of executive functioning were significant for urea cycle disorders, with concordance ranging from 52 to 80%. For the other metabolic disorders, correlations ranged from -0.09 to -0.55. Concordance rates for at-risk status on the BRIEF and executive functioning tests ranged from 55% in adults to 80% in children with other metabolic disorders. These results indicate that the ABAS-II and BRIEF together can confidently be used as an adjunct or supplementary method for clinical follow-up and for research on functional status involving infants, children, and adults with metabolic disorders.

Management of adult patients with phenylketonuria: survey results from 24 countries

Phenylketonuria (PKU) is no longer considered merely a pediatric concern; current guidelines recommend life-long treatment. However, information on the adult PKU patient population is scarce. A survey was initiated on behalf of the European PKU Group (EPG) that focused specifically on early-treated adult patients diagnosed by neonatal screening. The online survey was sent via email to 204 healthcare professionals (HCPs) in 33 countries. Eighty-one HCPs from 24 countries responded. The main findings were that the majority of adult patients with PKU in active follow-up are under 30 years of age and are managed in centers that also treat children. Seventy-eight percent of adult PKU patients in follow-up receive treatment, mainly by diet (71 %), with BH4 treatment rarely used in adulthood. Only 26 % of responding HCPs perform routine neurocognitive testing in all their adult patients. There was little consensus regarding target blood phenylalanine (Phe) concentrations, although the majority of respondents reported that their patients achieved blood Phe concentrations below 1200 μmol/l.

CONCLUSION

This survey highlights the need for blood Phe concentration target recommendations and consensus guidelines, more research into adult PKU patient management, and the need to identify those patients lost to follow-up to ensure PKU is managed for life.

Phenylketonuria Scientific Review Conference: state of the science and future research needs

New developments in the treatment and management of phenylketonuria (PKU) as well as advances in molecular testing have emerged since the National Institutes of Health 2000 PKU Consensus Statement was released. An NIH State-of-the-Science Conference was convened in 2012 to address new findings, particularly the use of the medication sapropterin to treat some individuals with PKU, and to develop a research agenda. Prior to the 2012 conference, five working groups of experts and public members met over a 1-year period. The working groups addressed the following: long-term outcomes and management across the lifespan; PKU and pregnancy; diet control and management; pharmacologic interventions; and molecular testing, new technologies, and epidemiologic considerations. In a parallel and independent activity, an Evidence-based Practice Center supported by the Agency for Healthcare Research and Quality conducted a systematic review of adjuvant treatments for PKU; its conclusions were presented at the conference. The conference included the findings of the working groups, panel discussions from industry and international perspectives, and presentations on topics such as emerging treatments for PKU, transitioning to adult care, and the U.S. Food and Drug Administration regulatory perspective. Over 85 experts participated in the conference through information gathering and/or as presenters during the conference, and they reached several important conclusions. The most serious neurological impairments in PKU are preventable with current dietary treatment approaches. However, a variety of more subtle physical, cognitive, and behavioral consequences of even well-controlled PKU are now recognized. The best outcomes in maternal PKU occur when blood phenylalanine (Phe) concentrations are maintained between 120 and 360 μmol/L before and during pregnancy. The dietary management treatment goal for individuals with PKU is a blood Phe concentration between 120 and 360 μmol/L. The use of genotype information in the newborn period may yield valuable insights about the severity of the condition for infants diagnosed before maximal Phe levels are achieved. While emerging and established genotype-phenotype correlations may transform our understanding of PKU, establishing correlations with intellectual outcomes is more challenging. Regarding the use of sapropterin in PKU, there are significant gaps in predicting response to treatment; at least half of those with PKU will have either minimal or no response. A coordinated approach to PKU treatment improves long-term outcomes for those with PKU and facilitates the conduct of research to improve diagnosis and treatment. New drugs that are safe, efficacious, and impact a larger proportion of individuals with PKU are needed. However, it is imperative that treatment guidelines and the decision processes for determining access to treatments be tied to a solid evidence base with rigorous standards for robust and consistent data collection. The process that preceded the PKU State-of-the-Science Conference, the conference itself, and the identification of a research agenda have facilitated the development of clinical practice guidelines by professional organizations and serve as a model for other inborn errors of metabolism.

Neuropsychological outcomes in fatty acid oxidation disorders: 85 cases detected by newborn screening

Mitochondrial fatty acid oxidation disorders include conditions in which the transport of activated acyl-Coenzyme A (CoA) into the mitochondria or utilization of these substrates is disrupted or blocked. This results in a deficit in the conversion of fat into energy. Most patients with fatty acid oxidation defects are now identified through newborn screening by tandem mass spectrometry. With earlier identification and preventative treatments, mortality and morbidity rates have improved. However, in the absence of severe health and neurological effects from these disorders, subtle developmental delays or neuropsychological deficits have been noted. Medical records were reviewed to identify outcomes in 85 children with FAOD's diagnosed through newborn screening and followed at one metabolic center. Overall, 54% of these children identified through newborn screening experienced developmental challenges. Speech delay or relative weakness in language was noted in 26 children (31%) and motor delays were noted in 24 children (29%). The majority of the 46 children receiving psychological evaluations performed well within the average range, with only 11% scoring <85 on developmental or intelligence tests. These results highlight the importance of screening children with fatty acid oxidation disorders to identify those with language, motor, or cognitive delay. Although expanded newborn screening dramatically changes the health and developmental outcomes in many children with fatty acid oxidation disorders, it also complicates the interpretation of biochemical and molecular findings and raises questions about the effectiveness or necessity of treatment in a large number of cases. Only by systematically evaluating developmental and neuropsychological outcomes using standardized methods will the true implications of newborn screening, laboratory results, and treatments for neurocognitive outcome in these disorders become clear.

Phenylalanine hydroxylase deficiency: diagnosis and management guideline

Phenylalanine hydroxylase deficiency, traditionally known as phenylketonuria, results in the accumulation of phenylalanine in the blood of affected individuals and was the first inborn error of metabolism to be identified through population screening. Early identification and treatment prevent the most dramatic clinical sequelae of the disorder, but new neurodevelopmental and psychological problems have emerged in individuals treated from birth. The additional unanticipated recognition of a toxic effect of elevated maternal phenylalanine on fetal development has added to a general call in the field for treatment for life. Two major conferences sponsored by the National Institutes of Health held >10 years apart reviewed the state of knowledge in the field of phenylalanine hydroxylase deficiency, but there are no generally accepted recommendations for therapy. The purpose of this guideline is to review the strength of the medical literature relative to the treatment of phenylalanine hydroxylase deficiency and to develop recommendations for diagnosis and therapy of this disorder. Evidence review from the original National Institutes of Health consensus conference and a recent update by the Agency for Healthcare Research and Quality was used to address key questions in the diagnosis and treatment of phenylalanine hydroxylase deficiency by a working group established by the American College of Medical Genetics and Genomics. The group met by phone and in person over the course of a year to review these reports, develop recommendations, and identify key gaps in our knowledge of this disorder. Above all, treatment of phenylalanine hydroxylase deficiency must be life long, with a goal of maintaining blood phenylalanine in the range of 120-360 µmol/l. Treatment has predominantly been dietary manipulation, and use of low protein and phenylalanine medical foods is likely to remain a major component of therapy for the immediate future. Pharmacotherapy for phenylalanine hydroxylase deficiency is in early stages with one approved medication (sapropterin, a derivative of the natural cofactor of phenylalanine hydroxylase) and others under development. Eventually, treatment of phenylalanine hydroxylase deficiency will be individualized with multiple medications and alternative medical foods available to tailor therapy. The primary goal of therapy should be to lower blood phenylalanine, and any interventions, including medications, or combination of therapies that help to achieve that goal in an individual, without other negative consequences, should be considered appropriate therapy. Significant evidence gaps remain in our understanding of the optimum therapies for phenylalanine hydroxylase deficiency, nonphenylalanine effects of these therapies, and long-term sequelae of even well-treated disease in children and adults.

Socio-emotional Problems in Children with CDG

BACKGROUND

Congenital disorders of glycosylation (CDG) form a group of inherited metabolic diseases. Although the clinical presentation shows extreme variability, the nervous system is frequently affected. Several parents of our patients diagnosed with CDG reported behavioral problems, including mood swings, depressive behavior, and anxiety. This raised the question whether patients with CDG have an increased risk for socio-emotional problems.

METHODS

We evaluated 18 children with confirmed CDG. The Child Behavior Checklist (CBCL) was used to screen for socio-emotional problems. To determine the disease progression and severity in CDG, the Nijmegen Paediatric CDG Rating Scale (NPCRS) was used. RESULTS were compared to "norm scores" and to children with mitochondrial disorders and children with other chronic metabolic disorders with multisystem involvement.

RESULTS

RESULTS showed a high prevalence of socio-emotional problems in children with CDG. Mean total scores, scores on withdrawn/depressed behavior, social problems, and somatic complaints were significantly increased. More than two thirds of our CDG patients have abnormal scores on CBCL. The mean score on social problems was significantly higher compared to our two control groups of patients with other chronic metabolic disorders.

CONCLUSIONS

Patients with CDG have an increased risk of developing socio-emotional problems. A standard screening for psychological problems is recommended for the early detection of psychological problems in CDG patients.

Neuropsychiatric Symptoms in Inborn Errors of Metabolism: Incorporation of Genomic and Metabolomic Analysis into Therapeutics and Prevention

Inborn errors of metabolism may present as a spectrum ranging from neonatal lethality to non-specific symptoms. Neuropsychiatric manifestations have been identified in three groups: those presenting as emergencies, those with chronic fluctuating symptoms, and those associated with mental retardation. Milder central nervous system specific inborn errors of metabolism may also present later in life with isolated psychiatric symptoms. Inborn errors of metabolism presenting with neuropsychiatric symptoms are described with illustrative case examples. Metabolomic and genomic approaches to identification and treatment are described.

A diversified approach for PKU treatment: routine screening yields high incidence of psychiatric distress in phenylketonuria clinics

OBJECTIVES

Individuals with phenylketonuria (PKU) treated early and continuously are reported to have psychiatric and executive function impairments. The feasibility of screening for psychiatric distress and executive function impairment in individuals with PKU was tested in 3 separate clinics in North America.

METHODS

Individuals were offered screening for psychiatric distress using the Pediatric Symptom Checklist, the PSC-Youth Report or the Brief Symptom Inventory and executive function impairment using the Behavior Rating Inventory of Executive Function. Gender, age and blood phenylalanine (Phe) concentrations obtained most recently and during the 2 years prior to screening were assessed.

RESULTS

More than 90% of patients with PKU accepted the screening for psychiatric distress during their routine clinic visit. The screening took 15-20 min. 32% of patients screened positive for psychiatric distress and 19% for executive function impairment. More individuals >18 years screened positive for psychiatric distress while a similar number screened positive for executive function impairment across age groups. Lower blood Phe levels correlated with negative screening for psychiatric distress. Patients positive for psychiatric distress had higher (p=0.009) median and most recent blood Phe values (p=0.05).

DISCUSSION/CONCLUSIONS

Routine screening for psychiatric distress of patients with phenylketonuria could be easily implemented in current clinic structures. High incidences of positive screens reinforce the need for regular psychiatric assessments of individuals with PKU. Identification and referral to local mental health providers might help to improve the standard of care for individuals with PKU.

Executive functioning in context: Relevance for treatment and monitoring of phenylketonuria

This paper presents findings from studies of EF in individuals with early-treated PKU within the context of recent advances in neuropsychological theory and research. It focuses on means of assessment, contexts of assessment, and the best way to define and investigate EF. Several conclusions can be drawn based on the findings presented here. The first conclusion is that there is clear evidence for phenylalanine-related EF-deficits in early-treated PKU, particularly with respect to prepotent response inhibition and the manipulation or monitoring component of working memory. An important note, however, is that measurement of EF in PKU has become too fragmented, as different researchers and clinicians use different definitions of EF, and subsequently, different instruments to measure EF. This appears to be one of the most important causes of mixed results. A second conclusion is that there appears to be a need to incorporate at least one specific, relatively new taxonomy of EF in PKU-research, i.e. the taxonomy that distinguishes hot and cool EFs, where hot EF is associated with regulation of affect/emotions and motivation, or regulatory functions when the context contains such elements, while cool EF concerns decontextualized regulatory abilities. PKU in adults is increasingly associated with different mental health problems, despite supposedly good treatment standards and adherence throughout childhood and adolescence. Since hot EF is strongly associated with such mental health problems, it is recommended that the hot-cool taxonomy will feature more prominently in future PKU-studies.

Recommendations for the use of sapropterin in phenylketonuria

Phenylketonuria (PKU) is an inherited disorder of phenylalanine (Phe) metabolism. Until recently, the only treatment for PKU was a Phe-restricted diet. Increasing evidence of suboptimal outcomes in diet-treated individuals, inconsistent PKU management practices, and the recent availability of tetrahydrobiopterin (BH(4)) therapy have fueled the need for new management and treatment recommendations for this metabolic disorder. BH(4), now available as sapropterin dihydrochloride (sapropterin), may offer the potential for improved metabolic control as well as enhanced dietary Phe tolerance in some PKU patients. A group of metabolic dietitians from North America convened in June 2011 to draft recommendations for the use of sapropterin therapy in PKU. Physicians with extensive experience in PKU management were invited at a later date to contribute to the development of these recommendations. Based on extensive clinical experience and current evidence, the present recommendations provide guidance from patient selection and determination of sapropterin response to the long-term management of patients on sapropterin therapy. Target Phe levels, nutritional adequacy, neurocognitive screening and adherence to treatment are addressed to optimize patient outcomes.

Outcomes of phenylketonuria with relevance to follow-up

Currently, there is no international consensus on how patients with phenylketonuria (PKU) (or milder forms of hyperphenylalaninaemia) should be followed in clinical practice. Guidelines concerning the frequency and type of assessments that should be made according to age usually focus on blood phenylalanine concentrations. A need exists for improved guidelines on how to do the follow-up of individuals with PKU/milder forms of hyperphenylalaninaemia. An interdisciplinary approach for monitoring patients is required, involving relevant clinical investigations and regular contact with a clinician and dietician/nutritionist as well as contact with social health worker, psychologist and neurologist, at least at request. This chapter presents a scheme for follow-up. However, by no means this scheme aims to present the one for all time follow-up programme. The scheme for follow-up may rather serve as a start for further discussion in larger groups of professionals in collaboration with patients and their parents. A number of questions remain unanswered, and further research is still needed to fine-tune the management of PKU at different ages.

Cognitive, neurophysiological, neurological and psychosocial outcomes in early-treated PKU-patients: a start toward standardized outcome measurement across development

The aim of this paper is to provide a concise summary of findings from outcome studies in early-treated phenylketonuria (PKU). The paper should not be considered as an extensive review of the many different outcome measures that have been used in PKU-research, but as an attempt to integrate such findings so that they will be of additional value for day to day monitoring of PKU-patients and may direct future research to fill the present gaps of knowledge. Neurological, neuropsychological, neurophysiological, neuroimaging, quality of life, and psychosocial findings will be discussed in the context of their potential contributions to lifelong follow-up and treatment of PKU-patients being summarized in statements.