Cognitive features that distinguish preschool-age children with neurofibromatosis type 1 from their peers: a matched case-control study

A Systematic Review on Visual-Processing Deficits in Neurofibromatosis Type 1: What Possible Impact on Learning to Read?

This systematic review aimed to examine the possible implication of visual-perceptual, visuo-attentional and oculomotor processing in the reading deficits frequently experienced by children with Neurofibromatosis type 1 (NF1), as previously shown in dyslexia. Using PRISMA methodological guidelines, we examined 49 studies; most of these reported visual-processing deficits in this population, raising the importance of directly studying the visuo-perceptual and visuo-attentional processes and eye-movement control involved in the learning-to-read process in NF1. The discussion provides a reflection for a better understanding of how visual-processing skills interact with reading deficits in NF1, as well as new avenues for their screening and care.

Benefits of intervention in the Central Auditory Nervous System in individuals with Neurofibromatosis Type 1

OBJECTIVE

To verify the effectiveness of acoustically controlled auditory training in individuals with Neurofibromatosis Type 1.

METHODS

The sample consisted of individuals with Neurofibromatosis Type 1, randomly distributed into two groups, making up the intervention group: individuals undergoing formal auditory training; and the comparison group: individuals who were not submitted to the intervention. Behavioral assessment of central auditory processing and electrophysiological evaluation, composed by Brainstem Auditory Evoked Potential and Long Latency-P300 Auditory Evoked Potential, were evaluated in three moments of evaluations: initial evaluation, reevaluation and after four months of reevaluation and comparing the performance between the groups.

RESULTS

Better performances in central auditory processing were observed after the formal auditory training in the intervention group with significant differences between the evaluations and performance maintenance four months after the end of the training. Significant differences were observed between the groups in the evaluations after the intervention. The electrophysiological evaluation shows unsystematic variation in the short latency potentials and changes in the long latency potentials with the appearance of the P3 wave after the intervention. The behavioral and electrophysiological evaluation in group that was not submitted to the intervention demonstrated that there is no improvement without the intervention, with deterioration of performance. Significant differences were observed in the behavioral and electrophysiological evaluations, in favor of the group submitted to formal auditory training.

CONCLUSIONS

Formal auditory training is effective in rehabilitation in individuals with Neurofibromatosis Type 1.

DESCRIPTORS/KEYWORDS

Neurofibromatosis 1; Hearing Disorders; Auditory Perceptual Disorders; Acoustic Stimulation; Evoked Potentials, Auditory.

School performance of children with neurofibromatosis 1: a nationwide population-based study

Children with neurofibromatosis 1 (NF1) may have a high burden of somatic disease and cognitive impairments, which can lead to poor academic performance. We evaluated school grades from exams ending mandatory schooling (usually around age 15 or 16 years) of children with NF1 in a population-based registry study using a within-school matched design. The study included 285 children with NF1 and 12,000 NF1-free peers who graduated from the same school and year during 2002-2015. We estimated overall and gender-specific grades by subject and compared the grades of children with NF1 with those of NF1-free peers in linear regression models. We also examined the effect of social and socioeconomic factors (immigration status and parental education, income and civil status) on grades and age at finalizing ninth grade. School grades varied considerably by socioeconomic stratum for all children; however, children with NF1 had lower grades by an average of 11-12% points in all subjects. In the adjusted models, children with NF1 had significantly lower grades than their NF1-free peers, with largest negative differences in grades observed for girls with NF1. Finally, children with NF1 were 0.2 (CI 0.1-0.2) years older than their peers on graduating from ninth grade, but only maternal educational modified the age at graduating. In conclusion, students with NF1 perform more poorly than their peers in all major school subjects. Gender had a strong effect on the association between NF1 and school grades; however, socioeconomic factors had a similar effect on grades for children with NF1 and their peers.

A systematic review and meta-analysis of intellectual, neuropsychological, and psychoeducational functioning in neurofibromatosis type 1

Neurofibromatosis Type 1 (NF1) is a common genetic disorder frequently associated with cognitive deficits. Despite cognitive deficits being a key feature of NF1, the profile of such impairments in NF1 has been shown to be heterogeneous. Thus, we sought to quantitatively synthesize the extant literature on cognitive functioning in NF1. A random-effects meta-analysis of cross-sectional studies was carried out comparing cognitive functioning of patients with NF1 to typically developing or unaffected sibling comparison subjects of all ages. Analyses included 50 articles (Total N_NF1 = 1,522; M_Age = 15.70 years, range = 0.52-69.60), yielding 460 effect sizes. Overall moderate deficits were observed [g = -0.64, 95% CI = (-0.69, -0.60)] wherein impairments differed at the level of cognitive domain. Deficits ranged from large [general intelligence: g = -0.95, 95% CI = (-1.12, -0.79)] to small [emotion: g = -0.37, 95% CI = (-0.63, -0.11)]. Moderation analyses revealed nonsignificant contributions of age, sex, educational attainment, and parental level of education to outcomes. These results illustrate that cognitive impairments are diffuse and salient across the lifespan in NF1. Taken together, these results further demonstrate efforts should be made to evaluate and address cognitive morbidity in patients with NF1 in conjunction with existing best practices.

Verbal learning and memory in youth with neurofibromatosis type 1 and plexiform neurofibromas: Relationships with disease severity

AIM

To provide a comprehensive characterization of verbal learning and memory (VLM) abilities in youth with neurofibromatosis type 1 (NF1) and plexiform neurofibromas (PNs) and to evaluate disease severity as a predictor of VLM functioning over time.

METHOD

As part of a longitudinal natural history study, youth with NF1 and PNs were administered repeat neuropsychological assessments, including measures of VLM and ratings of NF1 disease severity completed by a medical professional. This sub-study analyzed data from 89 patients (M age baseline = 13.1, SD = 4.3 years, range 6-24 years) who had completed tests of VLM abilities and verbal attention at either baseline and/or 36 months.

RESULTS

VLM scores across the sample fell predominantly within the average range of functioning at both time points. However, relative to peers with mild NF1 disease severity, youth with moderate/severe NF1 disease showed lower functioning across multiple VLM domains at 36 months, even after controlling for the effects of verbal attention.

INTERPRETATION

Exclusive use of overall domain scores does not fully characterize VLM functioning in youth with NF1 and PNs. Additionally, children and adolescents with more severe NF1 disease should be monitored more closely for verbal memory challenges and targeted for interventions.

Visuospatial but Not Verbal Working Memory Deficits in Adult Patients With Neurofibromatosis Type 1

Background: Cognitive dysfunction is one of the main symptoms of neurofibromatosis type 1 (NF1). As an important cognitive function, working memory (WM) has rarely been systematically analyzed in NF1 by isolating the particular domain of WM, and existing data involving WM in adult patients with NF1 are insufficient. This study aimed to investigate the characteristics of different types of WM in NF1 from the perspective of the adult population. Method: We comprehensively analyzed WM in both verbal and visuospatial WM domains by using the N-back task (including the verbal N-back task and the visuospatial N-back task) in 31 adults with NF1 and 34 healthy controls matched for age, gender, education levels, and general cognitive status. The accuracy and reaction times (RTs) in the N-back task were entered into mixed-design ANOVA. Results: Compared with healthy controls, adults with NF1 presented significantly lower mean accuracy and longer RTs in the visuospatial N-back task. However, no significant difference was found between the NF1 group and healthy controls in the verbal N-back task. Conclusions: The present study suggested that adults with NF1 might have deficits in visuospatial WM. We did not find evidence for verbal WM deficits in adult patients with NF1. Our findings supplement and refine the existing data on WM in the context of NF1.

Systemic Review and Meta-analysis of the Intellectual Integrity of Children with Neurofibromatosis Type 1

BACKGROUND

Cognitive impairment is a common neurologic complication of neurofibromatosis type 1 (NF-1) in childhood. A great number of learning disabilities appear in 30%-65% of children with NF-1. The aim of the study is to compare intelligence quotient (IQ) scores between children with NF-1 and comparable control groups.

METHODS

A literature review was conducted using the following databases: Cochrane, PubMed, Wiley, Microsoft Academic, and Google Scholar. We identified 180 papers. The pertinence of any study to the inclusion criteria was determined by assessing the title, key words, and abstracts. Data were extracted using multiple variables that were formulated incongruent with the study aim and then further analyzed.

RESULTS

Eleven articles met our criteria, with the highest level of evidence of 3c. A total of 483 NF1 and 443 control participants were included in this meta-analysis. The average and standard deviation of the age was 9.15 ± 3.15 years with an age range of 3.3-18 including 488 male and 438 female. The pooled estimate of the mean difference in all 3 parameters used full-scale IQ, verbal IQ, and performance IQ. Statistically, there was a significantly lower IQ in the NF-1 group compared with the control group with a 95% CI and (P < 0.00001).

CONCLUSION

The current meta-analysis illustrated a significant intellectual deficit in children with NF-1 compared with their typically developed peers who were matched by age. Performance IQ was significantly impaired compared with verbal IQ in NF-1 children. The current findings may guide experts to tailor individualized educational programs for children with NF-1.

Recommendations for Measurement of Attention Outcomes in Preschoolers With Neurofibromatosis

Children with neurofibromatosis type 1 (NF1) are at increased risk for attention problems. While most research has been conducted with school-aged cohorts, preschool-aged children offer a novel developmental window for clinical studies, with the promise that treatments implemented earlier in the developmental trajectory may most effectively modify risk for later difficulties. Designing research studies around the youngest children with NF1 can result in intervention earlier in the developmental cascade associated with NF1 gene abnormalities. Furthermore, clinical trials for medications targeting physical and psychological aspects of NF1 often include individuals spanning a wide age range, including preschool-aged children. In a prior report, the REiNS Neurocognitive Subcommittee made recommendations regarding performance-based and observer-rated measures of attention for use in clinical trials and highlighted the need for separate consideration of assessment methods for young children. The observer-rated Attention-Deficit/Hyperactivity Disorder Rating Scale-Preschool version is recommended as a primary outcome measure. The NIH Toolbox Flanker, Dimensional Change Card Sort, and List Sort Working Memory tasks and Digits Forward from the Differential Ability Scales-2nd Edition (performance-based measures) are recommended as secondary outcome measures. Specific methodologic recommendations for inclusion of preschoolers in clinical trials research are also offered.

Executive functions in preschool-aged children with neurofibromatosis type 1: Value for early assessment

Introduction: Executive functions (EFs) impairment is common in children with neurofibromatosis type 1 (NF1), and could be a significant vulnerability associated with this medical disorder. However, we still know little about EFs in preschool NF1. Our study assessed EFs in NF1 children using performance-based tests and daily life questionnaires, which combined the views of parents and teachers.Method: Seven classic experimental tasks were used to evaluate EFs in 33 NF1 children aged 3 to 5 years old, and BRIEF-P questionnaires were completed by their parents and teachers. These children's performance was compared with a control group of 52 healthy children matched in age, gender and socio-cultural status.Results: NF1 children have significantly lower scores for 5 out of 7 executive tasks than control children and significantly higher levels of EF concerns in the parent and teacher BRIEF-P ratings. The correlations between performance-based tests and questionnaires are weak.Conclusions: Our results support an early executive dysfunction in NF1 children and call for early and systematic assessment of EFs. Both performance-based tests and questionnaires are complementary tools to investigate early EFs dysfunction in children with NF1.

Sporadic and Familial Variants in NF1: An Explanation of the Wide Variability in Neurocognitive Phenotype?

Background: Cognitive impairment is the most common neurological manifestation in NF1 and occurs in 30–70% of NF1 cases. The onset and severity of each specific cognitive deficit varies greatly from child to child, with no apparent external causes. The wide variability of phenotype is the most complex aspect in terms of management and care. Despite multiple research, the mechanism underlying the high heterogeneity in NF1 has not yet been elucidated. While many studies have focused on the effects of specific and precise genetic mutations on the NF1 phenotype, little has been done on the impact of NF1 transmission (sporadic vs. familial cases). We used a complete neuropsychological evaluation designed to assess five large cognitive areas: general cognitive functions (WISC-IV and EVIP); reading skills (“L'Alouette,” ODEDYS-2 and Lobrot French reading tests); phonological process (ODEDYS-2 test); visual perceptual skills (JLO, Thurstone and Corsi block tests) and attention (CPT-II), as well as psychosocial adjustments (CBCL) to explore the impact of NF1 transmission on cognitive disease manifestation in 96 children affected by NF1 [55 sporadic cases (29♀, 26♂); 41 familial cases (24♀, 17♂)].

Results: Familial and Sporadic form of NF1 only differ in IQ expression. The families' socioeconomic status (SES) impacts IQ performance but not differently between sporadic and familial variants. However, SES is lower in familial variants than in the sporadic variant of NF1. No other cognitive differences emerge between sporadic and familial NF1.

Conclusions: Inheritance in NF1 failed to explain the phenotype variability in its entirety. IQ differences between groups seems in part linked to the environment where the child grows up. Children with NF1, and especially those that have early diagnoses (most often in inherited cases), must obtain careful monitoring from their early childhood, at home to strengthen investment in education and in school to early detect emerging academic problems and to quickly place them into care.

Trial Registration: IDRCB, IDRCB2008-A01444-51. Registered 19 January 2009.

Systematic Review and Meta-analysis of Executive Functions in Preschool and School-Age Children With Neurofibromatosis Type 1

OBJECTIVES

Neurofibromatosis type 1 (NF1) is a genetic disorder in which the most frequent complication in children is learning disabilities. Over the past decade, growing arguments support the idea that executive dysfunction is a core deficit in children with NF1. However, some data remain inconsistent. The aim of this study was to determine the magnitude of impairment for each executive function (EF) and clarify the impact of methodological choices and participant's characteristics on EFs.

METHODS

In this meta-analysis, 19 studies met the selection criteria and were included with data from a total of 805 children with NF1 and 667 controls. Based on the Diamond's model (2013), EF measures were coded separately according to the following EF components: working memory, inhibitory control, cognitive flexibility, planning/problem solving. The review protocol was registered with PROSPERO (International prospective register of systematic reviews; CRD42017068808).

RESULTS

A significant executive dysfunction in children with NF1 is demonstrated. Subgroup analysis showed that the impairment varied as a function of the specific component of executive functioning. The effect size for working memory and planning/problem solving was moderate whereas it was small for inhibitory control and cognitive flexibility. Executive dysfunction seems to be greater with increasing age whereas assessment tool type, intellectual performance, attention deficit hyperactivity disorder and control group composition did not seem to affect EF results.

CONCLUSIONS

EF deficits are a core feature in children with NF1 and an early identification of executive dysfunctions is essential to limit their impact on the quality of life. (JINS, 2018, 24, 977-994).

Preliteracy impairments in children with neurofibromatosis type 1

AIM

This cross-sectional study aimed to examine the preliteracy abilities of young children with neurofibromatosis type 1 (NF1) and to identify which of these abilities best predicted conventional literacy (spelling).

METHOD

Forty-two children with NF1 (23 males, 19 females; mean age [SD] 5y 6mo [6mo]) were compared with 32 unaffected children (15 males, 17 females; mean age [SD] 5y 4mo [6mo]). All children completed a comprehensive cognitive assessment including measures of phonological processing (phonological awareness, phonological memory, rapid automatic naming) and letter-sound knowledge.

RESULTS

Children with NF1 performed significantly poorer than the comparison group across all cognitive and preliteracy domains, with specific weaknesses evident in phonological awareness (F_1,68 =14.13, p<0.001, partial η² =0.17), phonological memory (F_1,68 =13.87, p<0.001, partial η² =0.17), and letter-sound knowledge (F_1,71 =5.65, p=0.020, partial η² =0.07). Within the group with NF1 group, over a third of children demonstrated impairment in at least one phonological processing domain and the risk of phonological impairment was 5.60 times that of unaffected children. Children's letter-sound knowledge was the strongest predictor of conventional literacy (spelling).

INTERPRETATION

This study establishes that preliteracy deficits are present and detectable in young children with NF1. As a result of the high incidence of preliteracy impairment, we recommend screening phonological awareness and letter-sound knowledge to identify risk of future learning disorders.

WHAT THIS PAPER ADDS

Young children with neurofibromatosis type 1 are at elevated risk of preliteracy deficits. The most affected domains are phonological awareness and phonological memory. Letter-sound knowledge is the strongest predictor of conventional literacy (spelling).

The Key Search Subtest of the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C) Instrument Reveals Impaired Planning Without External Constraints in Children With Neurofibromatosis Type 1

Studies of executive function and its relationship with brain T2-weighted hyperintensities in children with neurofibromatosis type 1 (NF1) have yielded inconsistent results. We examined 16 children with NF1 aged 8 to 15 years, of normal intelligence, and compared their findings to those of 16 siblings and 16 typically developing children using the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C). NF1 patients had an adequate overall score at BADS-C, but showed significantly lower performance than typical peers in the Key Search subtest. This is a task that must be solved without any given rules, in which subjects must devise a strategy and an efficient search pattern transferable to other similar real situations. The Key Search scores were not correlated with number and signal characteristics of T2-weighted hyperintensities. Planning without external indications is impaired in children with NF1 because they have to rely entirely on self-organization and monitoring; this study provides information for remediation programs designed to improve functioning in daily life.

Parent and Teacher Perspectives on Emerging Executive Functioning in Preschoolers With Neurofibromatosis Type 1: Comparison to Unaffected Children and Lab-Based Measures

Objective

Children with neurofibromatosis type 1 (NF1) are at risk for executive functioning (EF) challenges, with little research with preschoolers.

Methods

EF was examined using parent and teacher ratings of preschool-aged children with NF1 ( n  = 26) and parent ratings of unaffected children ( n  = 37) on the Behavior Rating Inventory for Executive Functioning-Preschool Form. Relations to performance on laboratory measures were also examined.

Results

Based on parent ratings, children with NF1 had more dysfunction than the normative mean on the Working Memory (WM) scale and Emergent Metacognition Index (EMI). Teacher ratings indicated greater dysfunction than the normative mean on the WM and Planning/Organization scales, EMI, and General Executive Composite. Children with NF1 showed more difficulties than unaffected children on the WM scale. Teacher report of WM was significantly correlated with Differential Ability Scales-Second Edition Digits Forward performance.

Conclusions

WM emerged as an area of difficulty for young children with NF1.

Early EEG Grade and Outcome at 5 Years After Mild Neonatal Hypoxic Ischemic Encephalopathy

OBJECTIVE

More than half of all infants with neonatal hypoxic ischemic encephalopathy (HIE) are graded as mild and do not meet current criteria for therapeutic hypothermia. These infants are often not enrolled in follow-up, and hence our knowledge of their long-term outcome is sparse. We wished to compare 5-year outcomes in a group of infants with mild, moderate, and severe HIE, graded with both early EEG and clinical assessment, none of whom were treated with therapeutic hypothermia.

METHODS

Term infants with HIE and a healthy comparison group were recruited at birth. Both groups had early continuous EEG recordings. Cognitive and motor outcome was assessed at 5 years.

RESULTS

Outcome was available in 53 infants with HIE and 30 infants in the comparison group at 5 years. Infants with mild HIE at birth (n = 22) had significantly lower full-scale IQ, verbal IQ, and performance IQ than comparison infants (n = 30) at 5 years (P = .001, .001, and 0.004, respectively). No difference in cognitive measures was seen between infants with mild and moderate grades HIE. Intact survival at 5 years varied across EEG grade HIE at 6 hours after birth; 75% in mild, 46% in moderate, 43% in major abnormalities, and 0% with inactive EEGs, compared with 97% in the comparison group.

CONCLUSIONS

Survivors of mild HIE, graded clinically or by early EEG, have higher rates of disability than their peers and have cognitive outcomes similar to that of children with moderate encephalopathy in an uncooled HIE cohort.

Developmental trajectories of young children with neurofibromatosis type 1: a longitudinal study from 21 to 40 months of age

OBJECTIVE

To establish the developmental trajectory of young children with neurofibromatosis type 1 (NF1) during the first 4 years of life.

STUDY DESIGN

In this longitudinal study, 39 children with NF1 and 39 controls were assessed with the Bayley Scales of Infant Development, Second Edition at 21 (time point 1, or T1) and 30 months (T2) of age, and the Wechsler Preschool and Primary Scale of Intelligence, Third Edition at 40 months (T3). Language was also assessed at T2 and T3. Parents rated their child's productive vocabulary at T1 and T2, and behavior at each time point. Linear mixed models were performed to examine cognitive development and behavior over time. Linear regressions were conducted to determine whether mental development and productive vocabulary at T1 or T2 predicted intellectual and language outcomes at T3.

RESULTS

Over time, the NF1 group had significantly lower cognitive scores than controls. Parent ratings indicated no group differences in behavior at each time point. Earlier mental function significantly predicted later general intelligence. Earlier productive vocabulary was a significant predictor of later language skills.

CONCLUSIONS

There are consistent differences over time in cognitive performance between children with NF1 and unaffected peers during the early childhood period. Earlier mental function and productive vocabulary are significant predictors of subsequent general intelligence and performance on language measures in NF1. This provides an opportunity for early identification and treatment for young children with NF1 who may show signs of impairments in these developmental domains.

Elucidating the impact of neurofibromatosis-1 germline mutations on neurofibromin function and dopamine-based learning

Neurofibromatosis type 1 (NF1) is a common autosomal dominant neurologic condition characterized by significant clinical heterogeneity, ranging from malignant cancers to cognitive deficits. Recent studies have begun to reveal rare genotype-phenotype correlations, suggesting that the specific germline NF1 gene mutation may be one factor underlying disease heterogeneity. The purpose of this study was to define the impact of the germline NF1 gene mutation on brain neurofibromin function relevant to learning. Herein, we employ human NF1-patient primary skin fibroblasts, induced pluripotent stem cells and derivative neural progenitor cells (NPCs) to demonstrate that NF1 germline mutations have dramatic effects on neurofibromin expression. Moreover, while all NF1-patient NPCs exhibit increased RAS activation and reduced cyclic AMP generation, there was a neurofibromin dose-dependent reduction in dopamine (DA) levels. Additionally, we leveraged two complementary Nf1 genetically-engineered mouse strains in which hippocampal-based learning and memory is DA-dependent to establish that neuronal DA levels and signaling as well as mouse spatial learning are controlled in an Nf1 gene dose-dependent manner. Collectively, this is the first demonstration that different germline NF1 gene mutations differentially dictate neurofibromin function in the brain.

NF1 regulation of RAS/ERK signaling is required for appropriate granule neuron progenitor expansion and migration in cerebellar development

Cerebellar development is regulated by a coordinated spatiotemporal interplay between granule neuron progenitors (GNPs), Purkinje neurons, and glia. Abnormal development can trigger motor deficits, and more recent data indicate important roles in aspects of memory, behavior, and autism spectrum disorders (ASDs). Germline mutation in the NF1 tumor suppressor gene underlies Neurofibromatosis type 1, a complex disease that enhances susceptibility to certain cancers and neurological disorders, including intellectual deficits and ASD. The NF1 gene encodes for neurofibromin, a RAS GTPase-activating protein, and thus negatively regulates the RAS signaling pathway. Here, using mouse models to direct conditional NF1 ablation in either embryonic cerebellar progenitors or neonatal GNPs, we show that neurofibromin is required for appropriate development of cerebellar folia layering and structure. Remarkably, neonatal administration of inhibitors of the ERK pathway reversed the morphological defects. Thus, our findings establish a critical cell-autonomous role for the NF1-RAS-ERK pathway in the appropriate regulation of cerebellar development and provide a basis for using neonatal ERK inhibitor-based therapies to treat NF1-induced cerebellar disorders.

Is there a relationship between executive functions and academic success in children with neurofibromatosis type 1?

The present study aimed to compare the executive function (EF) of children with neurofibromatosis type 1 (NF1) to those of typically developing children and to investigate whether those abilities could predict the child's academic success in terms of academic skills and enablers. Twenty-nine children with NF1 and 27 age-and-gender-matched controls (aged 8-16 years) were examined with two tests to measure EF in an ecologically valid manner: the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C) and the parent questionnaire for the Behavior Rating Inventory of Executive Function (BRIEF). In order to evaluate academic success we used the Academic Competence Evaluation Scales (ACES). The performance of the NF1 group was significantly lower on the Water and Key search subtest of the BADS-C and on four scales of the BRIEF: initiate; working memory; plan/organise and organisation of materials. Significant correlations and predictive models via regression analysis were generated for: BADS-C, BRIEF and ACES scores. Based on these findings, children with NF1 have executive dysfunction that partially accounts for their difficulties in academic achievements.