The relationship between working memory and anxiety in individuals with early treated phenylketonuria (PKU).

OBJECTIVE: Although early diagnosis and treatment prevent the severe impairments associated with untreated phenylketonuria (PKU), individuals with early treated PKU (ETPKU) nonetheless experience significant neurocognitive and psychological sequelae, including difficulties in working memory (WM) and increased risk of anxiety. The primary objective of the present study was to examine the extent to which anxiety may moderate the relationship between ETPKU and WM performance. METHOD: A sample of 40 adults with ETPKU and a demographically comparable sample of 40 healthy adults without PKU completed a comprehensive assessment of WM performance and anxiety symptomatology. Data were collected using a variety of remote assessment methods (e.g., web-based neurocognitive tests, semistructured interview, report-based measures). RESULTS: The ETPKU group demonstrated significantly poorer WM performance as compared to the non-PKU group. The groups did not differ significantly in anxiety; however, high anxiety was more common in the ETPKU group (53% of sample) than the non-PKU group (33%). A significant interaction between anxiety, metabolic control (as reflected by Phe levels), and WM performance was observed for the ETPKU group. Individuals with high anxiety and/or high Phe levels (> 360 µmol/L) performed poorer than the non-PKU group. Individuals with low anxiety and relatively low Phe levels (< 360 µmol/L) performed comparably to the non-PKU group. CONCLUSIONS: Anxiety was found to moderate the relationship between Phe levels and WM performance in individuals with ETPKU. This finding underscores the importance of accounting for anxiety when evaluating neurocognitive performance in individuals with ETPKU whether for research or clinical purposes. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Total choline intake and working memory performance in adults with phenylketonuria.

BACKGROUND: Despite early diagnosis and compliance with phenylalanine (Phe)-restricted diets, many individuals with phenylketonuria (PKU) still exhibit neurological changes and experience deficits in working memory and other executive functions. Suboptimal choline intake may contribute to these impairments, but this relationship has not been previously investigated in PKU. The objective of this study was to determine if choline intake is correlated with working memory performance, and if this relationship is modified by diagnosis and metabolic control. METHODS: This was a cross-sectional study that included 40 adults with PKU and 40 demographically matched healthy adults. Web-based neurocognitive tests were used to assess working memory performance and 3-day dietary records were collected to evaluate nutrient intake. Recent and historical blood Phe concentrations were collected as measures of metabolic control. RESULTS: Working memory performance was 0.32 z-scores (95% CI 0.06, 0.58) lower, on average, in participants with PKU compared to participants without PKU, and this difference was not modified by total choline intake (F[1,75] = 0.85, p = 0.36). However, in a subgroup with complete historical blood Phe data, increased total choline intake was related to improved working memory outcomes among participants with well controlled PKU (Phe = 360 µmol/L) after adjusting for intellectual ability and mid-childhood Phe concentrations (average change in working memory per 100 mg change in choline = 0.11; 95% CI 0.02, 0.20; p = 0.02). There also was a trend, albeit nonsignificant (p = 0.10), for this association to be attenuated with increased Phe concentrations. CONCLUSIONS: Clinical monitoring of choline intake is essential for all individuals with PKU but may have important implications for working memory functioning among patients with good metabolic control. Results from this study should be confirmed in a larger controlled trial in people living with PKU.

Characterization of Choline Nutriture among Adults and Children with Phenylketonuria.

Choline is an essential nutrient for brain development and function that is attained through high-protein foods, which are limited in the phenylalanine-restricted diet of people with phenylketonuria (PKU). This study compared choline consumption among individuals with PKU to a reference sample from the National Health and Nutrition Examination Survey (NHANES), and identified treatment and diet-related factors that may modulate choline needs. Participants were individuals with PKU (n = 120, 4-61 years) managed with dietary therapy alone (n = 49), sapropterin dihydrochloride for ≥1 year (n = 38), or pegvaliase for ≥1 year with no medical food (n = 33). NHANES participants were not pregnant or nursing and came from the 2015-2018 cycles (n = 10,681, 4-70 years). Dietary intake data were used to estimate total usual intake distributions for choline, and mean probability of adequacy (MPA) was calculated as a summary index of nutrient adequacy for four methyl-donor/co-factor nutrients that impact choline utilization (folate, vitamin B12, vitamin B6, and methionine). Only 10.8% (SE: 2.98) of the total PKU sample (14.7% [SE: 4.03] of children; 6.8% [SE: 2.89] of adults) achieved the adequate intake (AI) for choline, while 12.2% (SE:0.79) of the NHANES sample met the recommended level. Adults receiving pegvaliase were the most likely to exceed the AI for choline (14.82% [SE: 4.48]), while adults who were on diet therapy alone were the least likely (5.59% [SE: 2.95]). Without fortified medical foods, individuals on diet therapy and sapropterin would not be able to achieve the AI, and MPA for other methyl donor/co-factor nutrients would be reduced. More frequent monitoring of choline intake and increased choline fortification of medical foods could benefit this population.

Plasma metabolomic profile changes in females with phenylketonuria following a camp intervention.

BACKGROUND: There remains a limited understanding of the metabolic perturbations, beyond phenylalanine (Phe) metabolism, that contribute to phenotypic variability in phenylketonuria (PKU). OBJECTIVES: This study aimed to characterize changes in the PKU plasma metabolome following a 5-d metabolic camp intervention and to compare PKU profiles with those of matched healthy controls. METHODS: In 28 females (aged 12-57 y), fasting plasma samples were collected on the first (day 1) and final (day 5) days of camp to measure metabolic control and to complete untargeted metabolomic profiling. Three-day dietary records were collected to assess changes in dietary adherence and composition. Univariate (Wilcoxon signed-rank and Mann-Whitney U test) and multivariate (random forest, hierarchical clustering) analyses were performed to identify clinical and metabolic features that were associated with the intervention and disease state. RESULTS: Relative to healthy controls, Phe catabolites, ketones, and carnitine- and glycine-conjugated fatty acids were elevated in females with PKU at baseline, whereas fatty acylcholine metabolites were substantially lower. After the camp intervention, plasma Phe concentrations decreased [median change: -173 µmol/L (IQR: -325, -28 µmol/L)] and 70% of PKU participants demonstrated improved dietary adherence by decreasing Phe intake and/or increasing medical food consumption. This was accompanied by a shift in abundance for 223 metabolites (q < 0.05). Compounds associated with the metabolism of Phe, fatty acids, and choline contributed most to profile differences between camp days 1 and 5. CONCLUSIONS: In females with PKU, untargeted metabolomics identified prominent perturbations in amino acid and lipid metabolites associated with bioenergetic impairment and oxidative stress. Choline-conjugated lipids could have fundamental roles in these pathways and they have not been previously evaluated in PKU. A short-term camp intervention was effective for improving or fully normalizing the abundance of the identified discriminatory metabolites.