Cognitive and motor control in neurofibromatosis type I: influence of maturation and hyperactivity-inattention

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.

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.

Adolescents and young adults with neurofibromatosis type 1: A descriptive study of adaptive functioning

Neurofibromatosis type 1 (NF1) is a genetic syndrome affecting about 1 in 3500 individuals; many of those affected have plexiform neurofibroma (pNF) tumors and associated symptoms and complications. Furthermore, learning and attention problems, as well as deficits in adaptive functioning, are common, often beginning in early childhood. This study aimed to describe adaptive functioning and to examine relationships between adaptive functioning and cognitive and academic variables and level of independence among adolescents and young adults (AYA) with NF1 and pNF tumors. Fifty-five AYA aged 16-31 years participated in a series of neuropsychological evaluations while parents completed the Vineland Adaptive Behavior Scales (VABS-II) as part of a larger natural history study. Over one-third (35%) of AYA were neither in school nor employed. Mean VABS-II daily living and socialization scores were low average while mean Verbal and Performance IQ scores were average. VABS-II scores were positively correlated with processing speed, executive functioning, and working memory scores. Verbal IQ was the only significant predictor of work/school status. Identification of the correlates and predictors of adaptive functioning and life achievement can help guide healthcare providers with the early identification of risk factors and possible areas for intervention.

Intact procedural learning and motor intracortical inhibition in adult neurofibromatosis type 1 gene carriers

OBJECTIVE

Neurofibromatosis type 1 (NF1)¹ is known to cause learning deficits in affected individuals. There has been evidence linking altered gamma-aminobutyric acid (GABA)² mediated inhibition to learning impairments in rodent models and humans with NF1. Still, evidence on the role of GABA in learning deficits associated with NF1 is inconclusive.

METHODS

We examined procedural learning and motor cortex excitability through intracortical facilitation and short interval intracortical inhibition and its activity dependent modulation while performing a procedural sequence learning task in 16 asymptomatic NF1 gene carriers. We aimed to analyze potential brain-behavior correlations in a carefully selected sample of gene carriers in order to minimize confounding factors.

RESULTS

Gene carriers did not differ from healthy controls when learning the task with their non-dominant hand over three days of training. Electrophysiological data did not reveal alterations in patients' inhibitory function of the motor cortex.

CONCLUSIONS

In contrast with previous publications reporting various cognitive deficits in clinically asymptomatic individuals with NF1, here asymptomatic gene carriers did not show major neuropsychological or behavioral abnormalities.

SIGNIFICANCE

Our results support the concept that gene carriers may not always be impaired by the condition and the population of individuals with NF1 most likely comprises different subgroups according to patients' phenotype severity.

Cognitive and Electrophysiological Correlates of Working Memory Impairments in Neurofibromatosis Type 1

Neurofibromatosis 1 (NF1) is a single gene disorder associated with working Memory (WM) impairments. The aim of this study was to investigate P300 event-related potential (ERP) associated with WM in NF1. Sixteen adolescents with NF1 were compared with controls on measures of WM and EEG was recorded during a WM nback task. The NF1 group showed poorer performance on measures of WM as compared to the control group. No group differences were observed in P300 amplitude at Pz, but P300 latency was shorter in the NF1 group. Topographic analyses of P300 amplitude showed group differences indicating neural processing differences in the NF1 group relative to controls, which possibly contribute to the cognitive deficits seen in this population.

Attention and Executive Disorders in Neurofibromatosis 1: Comparison Between NF1 With ADHD Symptomatology (NF1 + ADHD) and ADHD Per Se

Objective: To compare children with Neurofibromatosis type 1 and associated ADHD symptomatology (NF1 + ADHD) with children having received a diagnosis of ADHD without NF1. The idea was that performance differences in tasks of attention between these two groups would be attributable not to the ADHD symptomatology, but to NF1 alone. Method: One group of children with NF1 + ADHD (N = 32), one group of children with ADHD (N = 31), and one group of healthy controls (N = 40) participated in a set of computerized tasks assessing intensive, selective, and executive aspects of attention. Results: Differences were found between the two groups of patients in respect of several aspects of attention. Children with NF1 + ADHD did not always perform worse than children with ADHD. Several double dissociations can be established between the two groups of patients. Conclusion: ADHD symptomatology in NF1 does not contribute to all attention deficits, and ADHD cannot account for all attention impairments in NF1.

An executive functioning perspective in neurofibromatosis type 1: from ADHD and autism spectrum disorder to research domains

PURPOSE

Neurofibromatosis type 1 (NF1) is a rare monogenic disorder associated with executive function (EF) deficits and heightened risk for attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). The goal of this paper is to understand how EFs provide a common foundation to understand vulnerabilities for ADHD and ASD within NF1.

METHODS

A literature review and synthesis was conducted.

RESULTS

EF difficulties in working memory, inhibitory control, cognitive flexibility, and planning are evident in NF1, ADHD, and ASD. However, relatively little is known about the heterogeneity of EFs and ADHD and ASD outcomes in NF1. Assessment of ADHD and ASD in NF1 is based on behavioral symptoms without understanding neurobiological contributions. Recent efforts are promoting the use of dimensional and multidisciplinary methods to better understand normal and abnormal behavior, including integrating information from genetics to self-report measures.

CONCLUSION

NF1 is a monogenic disease with well-developed molecular and phenotypic research as well as complementary animal models. NF1 presents an excellent opportunity to advance our understanding of the neurobiological impact of known pathogenic variation in normal and abnormal neural pathways implicated in human psychopathology. EFs are core features of NF1, ADHD, and ASD, and these neurodevelopmental outcomes are highly prevalent in NF1. We propose a multilevel approach for understanding EFs in patients with NF1.This is essential to advance targeted interventions for NF1 patients and to advance the exciting field of research in this condition.

Guanfacine treatment improves ADHD phenotypes of impulsivity and hyperactivity in a neurofibromatosis type 1 mouse model

Background

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with a mutation in one copy of the neurofibromin gene (NF1^+/−). Even though approximately 40–60% of children with NF1 meet the criteria for attention deficit hyperactivity disorder (ADHD), very few preclinical studies, if any, have investigated alterations in impulsivity and risk-taking behavior. Mice with deletion of a single NF1 gene (Nf1^+/−) recapitulate many of the phenotypes of NF1 patients.

Methods

We compared wild-type (WT) and Nf1^+/− mouse strains to investigate differences in impulsivity and hyperactivity using the delay discounting task (DDT), cliff avoidance reaction (CAR) test, and open field. We also investigated whether treatment with the clinically effective alpha-2A adrenergic receptor agonist, guanfacine (0.3 mg/kg, i.p.), would reverse deficits observed in behavioral inhibition.

Results

Nf1^+/− mice chose a higher percentage of smaller rewards when both 10- and 20-s delays were administered compared to WT mice, suggesting Nf1^+/− mice are more impulsive. When treated with guanfacine (0.3 mg/kg, i.p.), Nf1^+/− mice exhibited decreased impulsive choice by waiting for the larger, delayed reward. Nf1^+/− mice also exhibited deficits in behavioral inhibition compared to WT mice in the CAR test by repetitively entering the outer edge of the platform where they risk falling. Treatment with guanfacine ameliorated these deficits. In addition, Nf1^+/− mice exhibited hyperactivity as increased distance was traveled compared to WT controls in the open field. This hyperactivity in Nf1^+/− mice was reduced with guanfacine pre-treatment.

Conclusions

Overall, our study confirms that Nf1^+/− mice exhibit deficits in behavioral inhibition in multiple contexts, a key feature of ADHD, and can be used as a model system to identify alterations in neural circuitry associated with symptoms of ADHD in children with NF1.

Neuropsychological Consequences for Survivors of Childhood Brain Tumor in Malaysia

Objective: This study aimed to evaluate neuropsychological consequences in survivors of childhood brain tumor.

Method: A case-control study was conducted over a period of 4 months in a tertiary referral center in Kuala Lumpur, Malaysia. Fourteen survivors of childhood brain tumor aged 7–18 years, who were off-treatment for at least 1 year and were in remission, and 31 unrelated healthy controls were recruited. The median age at diagnosis was 8.20 years (range: 0.92–12.96 years). The diagnoses of brain tumors were medulloblastoma, germ cell tumor, pineocytoma, pilocystic astrocytoma, suprasellar germinoma, and ependymoma. Eleven survivors received central nervous system irradiation. Seven tasks were selected from the Amsterdam Neuropsychological Tasks program to evaluate alertness (processing speed), and major aspects of executive functioning, such as working memory capacity, inhibition, cognitive flexibility, and sustained attention. Speed, stability and accuracy of responses were the main outcome measures.

Results: Survivors of childhood brain tumor showed statistically significant poorer performance on all tasks compared to healthy controls. Both processing speed and accuracy were impaired in the survivors, in particular under more complex task conditions. The survivors demonstrated deficits in alertness, sustained attention, working memory capacity, executive visuomotor control, and cognitive flexibility. Longer duration off treatment appeared to be correlated with poorer alertness, memory capacity, and inhibition.

Conclusion: Survivors of childhood brain tumor in our center showed impaired neuropsychological functioning. Development of less toxic treatment protocols is important to prevent late effects of cognitive deficits in survivors of childhood brain tumor.

Oscillatory motor patterning is impaired in neurofibromatosis type 1: a behavioural, EEG and fMRI study

Background

Neurofibromatosis type1 (NF1) is associated with a broad range of behavioural deficits, and an imbalance between excitatory and inhibitory neurotransmission has been postulated in this disorder. Inhibition is involved in the control of frequency and stability of motor rhythms. Therefore, we aimed to explore the link between behavioural motor control, brain rhythms and brain activity, as assessed by EEG and fMRI in NF1.

Methods

We studied a cohort of 21 participants with NF1 and 20 age- and gender-matched healthy controls, with a finger-tapping task requiring pacing at distinct frequencies during EEG and fMRI scans.

Results

We found that task performance was significantly different between NF1 and controls, the latter showing higher tapping time precision. The time-frequency patterns at the beta sub-band (20–26 Hz) mirrored the behavioural modulations, with similar cyclic synchronization/desynchronization patterns for both groups. fMRI results showed a higher recruitment of the extrapyramidal motor system (putamen, cerebellum and red nucleus) in the control group during the fastest pacing condition.

Conclusions

The present study demonstrated impaired precision in rhythmic pacing behaviour in NF1 as compared with controls. We found a decreased recruitment of the cerebellum, a structure where inhibitory interneurons are essential regulators of rhythmic synchronization, and in deep brain regions pivotally involved in motor pacing. Our findings shed light into the neural underpinnings of motor timing deficits in NF1.

Boys with Oppositional Defiant Disorder/Conduct Disorder Show Impaired Adaptation During Stress: An Executive Functioning Study

Evidence for problems in executive functioning (EF) in children with oppositional defiant disorder/conduct disorder (ODD/CD) is mixed and the impact stress may have on EF is understudied. Working memory, sustained attention, inhibition and cognitive flexibility of boys with ODD/CD (n = 65) and non-clinical controls (n = 32) were examined under typical and stressful test conditions. Boys with ODD/CD showed impaired working memory under typical testing conditions, and impairments in working memory and sustained attention under stressful conditions. In contrast to controls, performance on sustained attention, cognitive flexibility and inhibition was less influenced by stress in boys with ODD/CD. These results suggest that boys with ODD/CD show impairments in adaptation to the environment whereas typically developing boys show adaptive changes in EF.

White matter microstructure of patients with neurofibromatosis type 1 and its relation to inhibitory control

Neurofibromatosis Type 1 (NF1) is commonly associated with deficits in executive functions such as working memory and inhibitory control. A valid biomarker to describe the pathological basis of these deficits in NF1 is not available. The aim of this study was to investigate whether any abnormalities in white matter integrity of the executive function related anterior thalamic radiation (ATR), cingulate bundle (CB), and superior longitudinal fasciculus (SLF) may be regarded as a pathological basis for inhibitory control deficits in adolescents with NF1. Sixteen NF1 patients and 32 healthy controls underwent 3 T DTI MRI scanning. Whole brain-, ATR-, CB-, and SLF-white matter integrity were studied using fractional anisotropy, mean (MD), radial, and axial (DA) diffusivity. Correlation analyses between white matter metrics and inhibitory control (as measured with a computerized task) were performed. Also, verbal and performance abilities (IQ-estimates) were assessed and correlated with white matter metrics. Patients showed significant whole brain- and local microstructural pathology when compared to healthy controls in all measures. In NF1-patients, whole-brain (MD: r = .646 and DA: r = .673) and ATR- (r-range: -.405-.771), but not the CB- (r-range: -.307-.472) and SLF- (r-range: -.187-.406) white matter integrity, were correlated with inhibitory control. Verbal and performance abilities were not associated with white matter pathology. In NF1, white matter abnormalities are observed throughout the brain, but damage to the ATR seems specifically, or at least most strongly related to inhibitory control. Future studies should examine whether reduced white matter integrity in other brain regions or tracts is (more strongly) associated with different aspects of the cognitive-behavioral phenotype associated with NF1.

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.

Conflict processing in juvenile patients with neurofibromatosis type 1 (NF1) and healthy controls - Two pathways to success

Neurofibromatosis Type 1 (NF1) is a monogenetic autosomal-dominant disorder with a broad spectrum of clinical symptoms and is commonly associated with cognitive deficits. Patients with NF1 frequently exhibit cognitive impairments like attention problems, working memory deficits and dysfunctional inhibitory control. The latter is also relevant for the resolution of cognitive conflicts. However, it is unclear how conflict monitoring processes are modulated in NF1. To examine this question in more detail, we used a system neurophysiological approach combining high-density ERP recordings with source localisation analyses in juvenile patients with NF1 and controls during a flanker task. Behaviourally, patients with NF1 perform significantly slower than controls. Specifically on trials with incompatible flanker-target pairings, however, the patients with NF1 made significantly fewer errors than healthy controls. Yet, importantly, this overall successful conflict resolution was reached via two different routes in the two groups. The healthy controls seem to arrive at a successful conflict monitoring performance through a developing conflict recognition via the N2 accompanied by a selectively enhanced N450 activation in the case of perceived flanker-target conflicts. The presumed dopamine deficiency in the patients with NF1 seems to result in a reduced ability to process conflicts via the N2. However, NF1 patients show an increased N450 irrespective of cognitive conflict. Activation differences in the orbitofrontal cortex (BA11) and anterior cingulate cortex (BA24) underlie these modulations. Taken together, juvenile patients with NF1 and juvenile healthy controls seem to accomplish conflict monitoring via two different cognitive neurophysiological pathways.

Cognitive and Behavioral Disorders in Children with Neurofibromatosis Type 1

AIM

The last systematic review of research on the behavior of children with neurofibromatosis type 1 (NF1) was in 2012. Since then, several important findings have been published. Therefore, the study aim was to synthesize recent relevant work related to this issue.

METHOD

We conducted a systematic review of the literature. Relevant articles were identified using the electronic databases PubMed, PsycINFO, and Scopus and a manual search of references lists. Thirty of 156 articles identified met the inclusion criteria. A quality evaluation of the articles was performed and the information was synthesized using a narrative approach.

RESULTS

Compared with controls, children and adolescents with NF1 present significant alterations in language, reading, visuospatial skills, motor function, executive function, attention, behavior, emotion, and social skills. The prevalence of attention-deficit/hyperactivity disorder (ADHD) is important and can affect cognition and executive function variables. A high prevalence of autistic traits and autistic spectrum disorder were reported. The benefits of using statins to treat cognitive deficits are unclear. However, children with NF1 and ADHD seem to benefit from methylphenidate treatment. The presence of hyperintensities in brain magnetic resonance imaging data seem to be related to poor cognitive performance. Analysis of these lesions could help to predict cognitive alterations in children with NF1.

INTERPRETATION

There has been important progress to evaluate cognitive characteristics of children with NF1 and to determine the physiological mechanisms of the concomitant disorders. However, discrepancies in relation to intelligence, learning disabilities, attention deficits, and treatment remain. Further investigations on this topic are recommended.

[Formula: see text]Executive functioning and its relation to ASD and ADHD symptomatology in 22q11.2 deletion syndrome

Children with 22q11.2 deletion syndrome (22q11DS; velo-cardio-facial-syndrome) are at risk for the developmental disorders, attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). In this study, the relation between executive functioning (EF) and the severity of ADHD and ASD symptoms is examined, since EF is known to be important in relation to emotional and behavioral problems. The participants consist of 58 children (38 females) with a mean age of 13.5 years (SD 2.6). Standardized assessment was used to evaluate the severity of ASD and ADHD symptomatology. The major aspects of EF, i.e., cognitive flexibility, inhibition, sustained attention, distractibility, working memory and reaction speed, were evaluated. The profile of EF in 22q11DS was found to be characterized by weaker performance compared to the norms on all subdomains of EF. Poor cognitive flexibility and inhibition, as well as high distractibility, were found to be related to more severe ASD symptoms, while poor quality of sustained attention and high distractibility were found to be related to more severe ADHD symptoms. It is concluded that children with 22q11DS experience impairments in EF, and that the degree of impairment on specific EF subdomains is related to the severity of ASD and/or ADHD symptomatology. These results may help in defining the mediating role of neurocognitive dysfunctions in the development of social and behavioral problems in 22q11DS.

Executive functioning deficits in children with neurofibromatosis type 1: The influence of intellectual and social functioning

The aim of this study was to provide a broad picture of Executive Functioning (EF) in NF1 children, while taking into account their lower average IQ and increased Autism Spectrum Disorder (ASD) symptoms. This was done by administering an extended battery of tasks and questionnaires, designed to reduce task impurity, that measures five EF domains (inhibition, cognitive flexibility, working memory, generativity and planning) in a laboratory setting and in daily life. Data are presented for 42 age- and gender-matched NF1, 52 typically developing, and 52 ASD children (8-18 years). Our results indicated that although EF is highly influenced by IQ and severity of ASD symptoms, EF deficits seem to be a core feature of NF1 and not merely a secondary effect of a lower IQ and/or increased ASD symptoms. However, additional research is needed to confirm these findings.

Executive Dysfunction 25 Years after Treatment with Cranial Radiotherapy for Pediatric Lymphoid Malignancies

The first cohorts to survive childhood lymphoid malignancies treated with cranial irradiation are now aging into adulthood, and concerns are growing about the development of radiotherapy-induced cognitive deficits in the aging brain. These deficits are hypothesized to increase over time. Their impact on daily functioning of older survivors, and the accompanying need for interventions, should be anticipated. By describing a detailed profile of executive function deficits and their associations with age, specific targets for neuropsychological intervention can be identified. Fifty survivors of childhood lymphoid malignancies and 58 related controls were assessed with the Amsterdam Neuropsychological Tasks program. The survivors were on average 31.1 (4.9) years old, treated with 22.5 (6.8) Gy cranial irradiation, and examined on average 25.5 (3.1) years after diagnosis. The survivors showed significantly decreased response speed, irrespective of the task at hand. Furthermore, we found deficits in working memory capacity, inhibition, cognitive flexibility, executive visuomotor control, attentional fluctuations, and sustained attention. Older age was associated with poorer performance on executive visuomotor control and inhibition. On executive visuomotor control, 50% of female survivors performed more than 1.5 SD below average, versus 15.4% of male survivors. The combination of visuospatial working memory problems and decreasing executive visuomotor control could result in difficulty with learning new motor skills at older ages, like walking with a cane. Deterioration of executive control and inhibition may result in decreased behavioral and emotional regulation in aging survivors. Especially the deficiency in executive visuomotor control in female survivors should be considered for (prophylactic) intervention.

Executive functioning profiles from the BRIEF across pediatric medical disorders: Age and diagnosis factors

The objective of the study was to compare executive functioning (EF) profiles across several pediatric medical conditions and explore the influence of age of diagnosis and evaluation. A retrospective, cross-sectional study of 734 children aged 5 to 18 years was conducted across five medical groups (brain tumor, leukemia [ALL], epilepsy [EPI], neurofibromatosis type 1 [NF1], and ornithine transcarbamylase deficiency [OTC-D]), attention deficit hyperactivity disorder (ADHD) controls, and matched healthy controls. We compared groups across the scales of a parent-completed Behavior Rating Inventory of Executive Functioning (BRIEF) using a repeated measures analysis of variance (ANOVA). Separate ANOVAs were conducted to look at age factors. The results showed that the ADHD group differed from all other groups and had the highest level of reported EF problems. The NF1 and OTC-D groups differed significantly from the healthy comparison group for overall EF problems, while the EPI and cancer groups did not. Working memory was the most elevated scale across medical groups, followed by plan/organize. Children with medical disorders were two to four times more likely than healthy controls to have clinically significant problems in several EF domains. There was a main effect for age at diagnosis and age at evaluation. A subset of children with medical disorders were found to have parent-reported EF difficulties, with particular vulnerability noted in working memory and organizational/planning skills. This has relevance for the development of interventions that may be helpful across disorders. Children with particular diagnoses and earlier age of diagnosis and evaluation had greater reported EF problems.

Abnormal relationship between GABA, neurophysiology and impulsive behavior in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a neurodevelopmental disorder characterized by a broad spectrum of cognitive deficits. In particular, executive dysfunction is recognized as a core deficit of NF1, including impairments in executive attention and inhibitory control. Yet, the neural mechanisms behind these important deficits are still unknown. Here, we studied inhibitory control in a visual go/no-go task in children and adolescents with NF1 and age- and gender-matched controls (n = 16 per group). We applied a multimodal approach using high-density electroencephalography (EEG), to study the evoked brain responses, and magnetic resonance spectroscopy (MRS) to measure the levels of GABA and glutamate + glutamine in the medial frontal cortex, a brain region that plays a pivotal role in inhibitory control, and also in a control region, the occipital cortex. Finally, we run correlation analyses to identify the relationship between inhibitory control, levels of neurotransmitters, and EEG markers of neural function. Individuals with NF1 showed impaired impulse control and reduced EEG correlates of early visual processing (parieto-occipital P1) and inhibitory control (frontal P3). MRS data revealed a reduction in medial frontal GABA+/tCr (total Creatine) levels in the NF1 group, in parallel with the already reported reduced occipital GABA levels. In contrast, glutamate + glutamine/tCr levels were normal, suggesting the existence of abnormal inhibition/excitation balance in this disorder. Notably, medial frontal but not occipital GABA levels correlated with general intellectual abilities (IQ) in NF1, and inhibitory control in both groups. Surprisingly, the relationship between inhibitory control and medial frontal GABA was reversed in NF1: higher GABA was associated with a faster response style whereas in controls it was related to a cautious strategy. Abnormal GABAergic physiology appears, thus, as an important factor underlying impaired cognition in NF1, in a level and region dependent manner.

Relations between fine motor skill and parental report of attention in young children with neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is one of the most common genetic disorders presenting in approximately 1 in 3,500 live births. NF1 is a highly variable condition with a large number of complications. A common complication is neuropsychological problems, including developmental delays and learning difficulties that affect as many as 60% of patients. Research has suggested that school-aged children with NF1 often have poorer fine motor skills and are at greater risk for attention difficulties than the general population. Thirty-eight children with NF1 and 23 unaffected children between the ages of 4 and 6 years, who are enrolled in a study of early development in NF1, were included in the present study. Varying levels of fine motor functioning were examined (simple to complex fine motor tasks). For children with NF1, significant difficulties were demonstrated on lab-based mid-level and complex fine motor tasks, even after controlling for nonverbal reasoning abilities, but not on simple fine motor tasks. Parental report also indicated difficulties in everyday adaptive fine motor functioning. No significant correlations were found between complex fine motor ability and attention difficulties. This study provides much needed descriptive data on the early emergence of fine motor difficulties and attention difficulties in young children with NF1.

Language in young children with neurofibromatosis-1: relations to functional communication, attention, and social functioning

In this study, the language abilities of 30 children with Neurofibromatosis Type 1 (NF1) aged 4-6 years were examined using a standardized measure of language. Relations of language to multiple parental report measures of functional communication, social skills, and attention problems were investigated. Difficulties in core language skills were observed, and more than 1/3 of the children struggled on at least one language index. Language abilities were significantly related to parental report of functional communication, social interaction and communication, and social skills, such that language difficulties may be a risk factor for communication and social interaction challenges and communication-related adaptive behavior in children with NF1. Though receptive language abilities were an area of particular difficulty for many children with NF1, they were not significantly related to parental ratings of social functioning and functional communication. Few significant relations were found between language and parent-reported attention problems, although some trends were noted. Hence attention difficulties in children with NF1 may contribute to, but do not appear to fully account for, language difficulties. In sum, there is an increased risk of language difficulties for young children with NF1, and lab-measured language difficulties appear to relate to everyday communication and social interaction functioning.

Cognitive and behavioral problems in children with neurofibromatosis type 1: challenges and future directions

Cognitive and behavioral disorders affect nearly 80% of all children with the neurofibromatosis type 1 inherited cancer syndrome, and are among the most significant clinical manifestations for patients and their families. One of the barriers to successful therapeutic intervention is the wide spectrum of clinical phenotypic expression, ranging from visuospatial learning problems to social perceptual deficits (autism). Leveraging numerous small-animal models of neurofibromatosis type 1, several promising targets have been identified to treat the learning, attention, and autism spectrum phenotypes in this at-risk population. In this review, we provide an up-to-date summary of our current understanding of these disorders in NF1, and propose future research directions aimed at designing more effective therapeutic approaches and clinical trials.

Neuropsychological profile in adults with neurofibromatosis type 1 compared to a control group

BACKGROUND

Neurofibromatosis type 1 (NF1) is a common inherited autosomal dominant condition, characterised by multiple café-au-lait macules, axillary and/or inguinal freckling, iris Lisch nodules and tumours of the nervous system such as neurofibromas and optic pathway gliomas. At the same time, NF1 is frequently associated with intellectual disabilities across several neuropsychological domains. Existing neuropsychological data in NF1 adults are limited and sometimes contradictory. Moreover, most studies use a non-IQ-controlled norm group for comparison. This study sought to investigate specific neuropsychological characteristics in intellectual abilities unrelated to the global intellectual capacity.

METHOD

Twenty NF1 adults and an IQ-, age- and gender-matched control group completed a comprehensive neuropsychological test battery composed of specific cognitive tests investigating visual-spatial abilities and memory, auditory memory, selective and sustained attention and executive functioning. A short version of the Wechsler Adult Intelligence Scale - III was also administered to both groups.

RESULTS

Norm comparison showed that both groups perform poorly on most neuropsychological functions, except for sustained attention. However, comparison with the IQ-matched control group showed significantly lower scores on visual-spatial abilities and memory, on auditory working memory and on tests for cognitive flexibility in NF1 adults. Nevertheless, as the significant difference in average estimated IQ score between the NF1 group and the selected control group almost reaches the 5% significance level, further analysis is needed to include IQ as a covariate. Eventually, problems in visual-spatial skills and auditory long-term memory seem to be specific NF1-related deficits, while problems in attention and executive functioning are particularly related to their general lowered intellectual abilities.

CONCLUSION

Taking into account that primary visual perception problems could be part of a more general central coherence deficit while interpreting auditory memory problems as possibly related to deficits in language use and comprehension, this idea also fits with the observation of several problems in social information processing and functioning of NF1 persons.

Accelerated aging, decreased white matter integrity, and associated neuropsychological dysfunction 25 years after pediatric lymphoid malignancies

PURPOSE

CNS-directed chemotherapy (CT) and cranial radiotherapy (CRT) for childhood acute lymphoblastic leukemia or lymphoma have various neurotoxic properties. This study aimed to assess their impact on the maturing brain 20 to 30 years after diagnosis, providing a much stronger perspective on long-term quality of life than previous studies.

PATIENTS AND METHODS

Ninety-three patients treated between 1978 and 1990 at various intensities, with and without CRT, and 49 healthy controls were assessed with magnetic resonance diffusion tensor imaging (DTI) and neuropsychological tests. Differences in fractional anisotropy (FA)-a DTI measure describing white matter (WM) microstructure-were analyzed by using whole brain voxel-based analysis.

RESULTS

CRT-treated survivors demonstrated significantly decreased FA compared with controls in frontal, parietal, and temporal WM tracts. Trends for lower FA were seen in the CT-treated survivors. Decreases in FA correlated well with neuropsychological dysfunction. In contrast to the CT group and controls, the CRT group showed a steep decline of FA with age at assessment. Younger age at cranial irradiation and higher dosage were associated with worse outcome of WM integrity.

CONCLUSION

CRT-treated survivors show decreased WM integrity reflected by significantly decreased FA and associated neuropsychological dysfunction 25 years after treatment, although effects of CT alone seem mild. Accelerated aging of the brain and increased risk of early onset dementia are suspected after CRT, but not after CT.

A neuropsychological perspective on attention problems in neurofibromatosis type 1

Cognitive problems are common in children with neurofibromatosis type 1 and they can often complicate treatment. The current literature review examines cognitive functioning in neurofibromatosis type 1, with a specific focus on executive functioning. This includes exploration of how deficits in executive functioning are expressed in children with neurofibromatosis type 1 and how these deficits contrast with ADHD. The value of investigating subcomponents of executive functioning is discussed, as are implications for effective treatment and future research.

Impaired response inhibition in autism spectrum disorders, a marker of vulnerability to schizophrenia spectrum disorders?

In this study, we addressed the relation between specific deficits in cognitive control and schizotypal symptomatology in adolescents with autism spectrum disorders (ASD) diagnosed in childhood. We aimed to identify cognitive control deficits as markers of vulnerability to the development of schizophrenia spectrum pathology in ASD. Symptoms of autism and the risk for schizotypal symptomatology were assessed in 29 high-functioning adolescents with ASD, and compared with 40 typically developing adolescents. Cognitive control (response inhibition, mental flexibility, visuo-motor control, interference control, and perseveration) was evaluated for specific association with schizotypal symptomatology. Impaired response inhibition appeared to be strongly and specifically associated with schizotypal symptomatology in adolescents with ASD, especially those with positive and disorganized symptoms. Response inhibition problems could indicate vulnerability to the development of schizotypal symptomatology in ASD.

Behaviour in children with neurofibromatosis type 1: cognition, executive function, attention, emotion, and social competence

AIM

This systematic review aimed to pull together the findings from research into behavioural systems and attention in children with neurofibromatosis type 1 (NF1) and to identify areas that need further study.

METHOD

Relevant papers were identified through searches of electronic databases (MEDLINE, PsycINFO, EMBASE) and manual searches through reference lists. In total, 5746 articles were identified and 57 met the inclusion criteria. The data were synthesized using the narrative approach, as the studies varied considerably in terms of participants and measures.

RESULTS

The results of the review showed that intelligence, academic skills, visuospatial skills, social competence, and attention are impaired in children with NF1. Evidence of deficits in memory, motor functioning, language, and executive functions was less clear.

INTERPRETATION

Research has made marked progress in outlining the behavioural phenotype of NF1. However, although the general areas of impairment are becoming better known, the exact nature of the impairment is still not understood in many areas of behaviour. Care needs to be taken with the way in which behavioural constructs are defined and measured, and the variability of problems in NF1 is a particular challenge. Nevertheless, research is steadily moving towards comprehensive understanding of behaviour in children with NF1.

Does attention-deficit-hyperactivity disorder exacerbate executive dysfunction in children with neurofibromatosis type 1?

AIM

Although approximately 40% of children with neurofibromatosis type 1 (NF1) meet diagnostic criteria for attention-deficit-hyperactivity disorder (ADHD), the impact of ADHD on the executive functioning of children with NF1 is not understood. We investigated whether spatial working memory and response inhibition are impaired in children with NF1 without a diagnosis of ADHD and whether executive deficits are exacerbated in children with a comorbid diagnosis.

METHOD

Forty-nine children aged 7 to 15 years with NF1 only (31 males, 18 females; mean age 11y, SD 2y 4mo) or 35 with NF1 and ADHD (18 males, 17 females; mean age 10y 8mo, SD 2y 4mo) and 30 typically developing comparison children (16 males, 14 females; mean age 10y, SD 2y 8mo) were compared on measures of spatial working memory and response inhibition. Group differences in IQ and visuospatial ability were controlled for as required.

RESULTS

Compared with typically developing children, children with NF1 with or without comorbid ADHD demonstrated significant impairment of both spatial working memory (both p<0.004) and inhibitory control (both p<0.010). There were, however, no differences between the two NF1 groups in spatial working memory (p=0.91) or response inhibition (p=0.78).

INTERPRETATION

Executive dysfunction occurs with the same severity in children with NF1, whether or not they have a comorbid diagnosis of ADHD, suggesting that executive impairments are not unique contributors to ADHD symptomatology in NF1. The findings are discussed within the context of recent evidence in Nf1 optic glioma (OPG) mice, in which a mechanistic connection between NF1 gene expression, executive system failure, and dopaminergic pathway integrity has been established.

Long-term effects of cranial irradiation and intrathecal chemotherapy in treatment of childhood leukemia: a MEG study of power spectrum and correlated cognitive dysfunction

Background

Prophylaxis to prevent relapses in the central nervous system after childhood acute lymphoblastic leukemia (ALL) used to consist of both intrathecal chemotherapy (CT) and cranial irradiation (CRT). CRT was mostly abolished in the eighties because of its neurotoxicity, and replaced with more intensive intrathecal CT. In this study, a group of survivors treated with CRT before 1983 and another group treated without CRT thereafter are investigated 20–25 years later, giving a much stronger perspective on long-term quality of life than previous studies. The outcomes will help to better understand these groups’ current needs and will aid in anticipating late effects of prophylactic CRT that is currently applied for other diseases. This study evaluates oscillatory neuronal activity in these long-term survivors. Power spectrum deviations are hypothesized to correlate with cognitive dysfunction.

Methods

Resting state eyes-closed magnetoencephalography (MEG) recordings were obtained from 14 ALL survivors treated with CT + CRT, 18 treated with CT alone and 35 controls. Relative spectral power was calculated in the δ, θ, α1, α2, β and γ frequency bands. The Amsterdam Neuropsychological Tasks (ANT) program was used to assess cognition in the executive functions domain. MEG data and ANT scores were correlated.

Results

In the CT + CRT group, relative θ power was slightly increased (p = 0.069) and α2 power was significantly decreased (p = 0.006). The CT + CRT group performed worse on various cognitive tests. A deficiency in visuomotor accuracy, especially of the right hand, could be clearly associated with the deviating regional θ and α2 powers (0.471 < r < 0.697). A significant association between decreased regional α2 power and less attentional fluctuations was found for CT + CRT patients as well as controls (0.078 < r < 0.666). Patients treated with CT alone displayed a power spectrum similar to controls, except for a significantly increased level of left frontal α2 power (p = 0.030).

Conclusions

The tendency towards global slowing of brain oscillatory activity, together with the fact that dementia has been reported as a late effect of CRT and the neuropsychological deficiencies currently present, suggest that the irradiated brain might be aging faster and could be at risk for early‐onset dementia. The CT group showed no signs of early aging.

Abnormal brain activation in neurofibromatosis type 1: a link between visual processing and the default mode network

Neurofibromatosis type 1 (NF1) is one of the most common single gene disorders affecting the human nervous system with a high incidence of cognitive deficits, particularly visuospatial. Nevertheless, neurophysiological alterations in low-level visual processing that could be relevant to explain the cognitive phenotype are poorly understood. Here we used functional magnetic resonance imaging (fMRI) to study early cortical visual pathways in children and adults with NF1. We employed two distinct stimulus types differing in contrast and spatial and temporal frequencies to evoke relatively different activation of the magnocellular (M) and parvocellular (P) pathways. Hemodynamic responses were investigated in retinotopically-defined regions V1, V2 and V3 and then over the acquired cortical volume. Relative to matched control subjects, patients with NF1 showed deficient activation of the low-level visual cortex to both stimulus types. Importantly, this finding was observed for children and adults with NF1, indicating that low-level visual processing deficits do not ameliorate with age. Moreover, only during M-biased stimulation patients with NF1 failed to deactivate or even activated anterior and posterior midline regions of the default mode network. The observation that the magnocellular visual pathway is impaired in NF1 in early visual processing and is specifically associated with a deficient deactivation of the default mode network may provide a neural explanation for high-order cognitive deficits present in NF1, particularly visuospatial and attentional. A link between magnocellular and default mode network processing may generalize to neuropsychiatric disorders where such deficits have been separately identified.

Developmental delays in children with neurofibromatosis type 1

It is well documented that children with neurofibromatosis type 1 are at high risk for a variety of cognitive and learning deficits. The current study investigated the use of a developmental screening tool, the Parents' Evaluation of Developmental Status: Developmental Milestones, as an accurate, reliable, and efficient indicator of developmental delays. Sixty-eight percent of children with neurofibromatosis type 1 were found to have a developmental delay in at least 1 of the 8 areas tested by the Parents' Evaluation of Developmental Status: Developmental Milestones. Significant developmental abnormalities were found in the areas of fine motor (35%), gross motor (52%), and math/premath (31%). A positive association was found between the presence of a previously diagnosed optic glioma and math/premath delays (χ(2) = 0.0022) and between male sex and fine motor delays (χ(2) = 0.0325). The Parents' Evaluation of Developmental Status: Developmental Milestones assessment demonstrates the high presence of developmental delays in children with neurofibromatosis type 1 and the need for aggressive and early screening.

Social-emotional functioning of children and adolescents with neurofibromatosis type 1 and plexiform neurofibromas: relationships with cognitive, disease, and environmental variables

OBJECTIVE

This descriptive cross-sectional study aimed to determine how cognitive, disease, and environmental variables relate to social-emotional functioning in youth with NF1 and plexiform neurofibromas.

METHODS

Psychological assessments were administered to 53 children (mean age 12.4 years); parents and teachers completed the behavior assessment system for children-second edition (BASC-2). Disease severity was quantified by nurse-practitioner ratings and tumor burden, and parents completed a life events checklist to indicate environmental stressors.

RESULTS

Notable proportions of children scored in the at-risk/clinically significant ranges on several parent and teacher BASC-2 subscales including somatization, attention problems, depression, and withdrawal. Combinations of cognitive, disease, and environmental variables predicted scores on parent BASC-2 internalizing problems, behavior symptoms index, and Adaptive Skills composites.

CONCLUSIONS

Cognitive, disease, and environmental variables relate to social-emotional outcomes in children with NF1. These youth may benefit from interventions targeting social skills, cognitive functioning, and adaptive ways of coping with NF1-related pain.

Does cognitive impairment explain behavioral and social problems of children with neurofibromatosis type 1?

Thirty NF1-patients (mean age 11.7 years, SD = 3.3) and 30 healthy controls (mean age 12.5 years, SD = 3.1) were assessed on social skills, autistic traits, hyperactivity-inattention, emotional problems, conduct problems, and peer problems. Cognitive control, information processing speed, and social information processing were measured using 5 computer tasks. GLM analyses of variance showed significant group differences, to the disadvantage of NF1-patients, on all measures of behavior, social functioning and cognition. General cognitive ability (a composite score of processing speed, social information processing, and cognitive control) accounted for group differences in emotional problems, whereas social information processing accounted for group differences in conduct problems. Although reductions were observed for group differences in other aspects of behavior and social functioning after control for (specific) cognitive abilities, group differences remained evident. Training of cognitive abilities may help reducing certain social and behavioral problems of children with NF1, but further refinement regarding associations between specific aspects of cognition and specific social and behavioral outcomes is required.