Emotional and behavioral problems in children and adolescents with neurofibromatosis type 1.

To assess emotional and behavioral problems in children and adolescents with neurofibromatosis type 1,parents of 183 individuals aged 10.8 ± 3.1 years (range 6-17) completed the Child Behavior Checklist (CBCL). Also, 173 teachers completed the Teacher's Report Form (TRF), and 88 adolescents (children from 11 to 17 years) completed the Youth Self-Report (YSR). According to parental ratings, 32% scored in the clinical range (above the 90th percentile). This percentage was much lower when rated by teachers or adolescents themselves. Scores from all informants on scales for Somatic complaints, Social problems, and Attention problems were significantly different from normative scores. Attentional problems were associated with lower verbal IQ, male gender, younger age, and ADHD-symptoms. Disease-related factors did not predict behavioral problems scores. Substantial emotional and behavioral problems were reported by parents, teachers, and to a lesser extent by adolescents with NF1 themselves. Possibly, a positive illusory bias affects the observation of behavioral problems by adolescents with NF1.

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.

Prevalence of Autism Spectrum Disorder symptoms in children with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic condition. While considerable work has focused on cognitive functioning, several research groups also observed difficulties in social functioning as a prominent feature of NF1. These problems and the possible link between NF1 and Autism Spectrum Disorder (ASD) have become increasingly important in recent NF1 literature. The aim of the current study was to assess ASD characteristics in a hospital-based NF1 pediatric population (n = 82) using the standardized Children Social Behavior Questionnaire (CSBQ) and Social Responsiveness Scale (SRS) to account for the prevalence, severity, and nature of social problems. In a parallel study, comprehensive ASD assessment was performed in a subgroup of NF1 children with a strong suspicion of ASD (n = 31). Results indicate that NF1 children have more social problems than typical controls, more frequently reported above 8 years. The SRS shows that 63% is at risk of ASD symptoms. According to item analyses, most problems were observed on items measuring orientation in, understanding of and being tuned onto a social situation (CSBQ) and social cognition and communication (SRS). In the parallel study, 27 NF1 children were diagnosed with ASD. These children have a distinct phenotype compared to a heterogeneous ASD group, with pronounced social-communicative impairments and fewer restrictive/repetitive behaviors. This study provides a better understanding of social problems in NF1 and the phenotypical overlap with ASD symptomatology. Despite their willingness to engage with others, NF1 children with or without ASD encounter various difficulties in their social-communicative life.

Observations on intelligence and behavior in 15 patients with Legius syndrome.

Legius syndrome is a RAS-MAPK syndrome characterized by pigmentary findings similar to neurofibromatosis type 1 (NF1), but without tumor complications. Learning difficulties and behavioral problems have been reported to be associated with Legius syndrome, but have not been studied systematically. We investigated intelligence and behavior in 15 patients with Legius syndrome and 7 unaffected family members. We report a mean full-scale IQ of 101.57 in patients with Legius syndrome, which does not differ from the control group. We find a significantly lower Performance IQ in children with Legius syndrome compared to their unaffected family members. Few behavioral problems are present as assessed by the Child Behavior Checklist (CBCL) questionnaire. Our observations suggest that, akin to the milder somatic phenotype, the cognitive phenotype in Legius syndrome is less severe than that of NF1.

The effect of early life stress on the cognitive phenotype of children with an extra X chromosome (47,XXY/47,XXX).

Studies on gene-environment interactions suggest that some individuals may be more susceptible to life adversities than others due to their genetic profile. This study assesses whether or not children with an extra X chromosome are more vulnerable to the negative impact of early life stress on cognitive functioning than typically-developing children. A total of 50 children with an extra X chromosome and 103 non-clinical controls aged 9 to 18 years participated in the study. Cognitive functioning in domains of language, social cognition and executive functioning were assessed. Early life stress was measured with the Questionnaire of Life Events. High levels of early life stress were found to be associated with compromised executive functioning in the areas of mental flexibility and inhibitory control, irrespective of group membership. In contrast, the children with an extra X chromosome were found to be disproportionally vulnerable to deficits in social cognition on top of executive dysfunction, as compared to typically-developing children. Within the extra X group the number of negative life events is significantly correlated with more problems in inhibition, mental flexibility and social cognition. It is concluded that children with an extra X chromosome are vulnerable to adverse life events, with social cognition being particularly impacted in addition to the negative effects on executive functioning. The findings that developmental outcome is codependent on early environmental factors in genetically vulnerable children also underscores opportunities for training and support to positively influence the course of development.

Autism spectrum disorder profile in neurofibromatosis type I.

Neurofibromatosis Type 1 (NF1) is a common autosomal dominant single-gene disorder, in which the co-occurrence of autism spectrum disorder (ASD) has attracted considerable research interest recently with prevalence estimates of 21-40%. However, detailed characterization of the ASD behavioral phenotype in NF1 is still lacking. This study characterized the phenotypic profile of ASD symptomatology presenting in 4-16 year old children with NF1 (n = 36) using evidence from parent-rated Social Responsiveness Scale and researcher autism diagnostic observation Scale-2. Compared to IQ-matched reference groups of children with autism and ASD, the NF1 profile shows overall similarity but improved eye contact, less repetitive behaviors and better language skills.

Simvastatin for cognitive deficits and behavioural problems in patients with neurofibromatosis type 1 (NF1-SIMCODA): a randomised, placebo-controlled trial.

BACKGROUND: Neurofibromatosis type 1 is a common genetic disorder characterised by neurocutaneous manifestations and cognitive and behavioural problems. Statins were shown to reduce analogous learning deficits in a mouse model of the disease, but a short-term trial in humans was inconclusive. We aimed to assess the use of simvastatin for the improvement of cognitive and behavioural deficits in children with neurofibromatosis type 1 for 12 months. METHODS: In this randomised, double-masked, placebo-controlled trial, we recruited children with genetically confirmed neurofibromatosis type 1 aged 8-16 years from two national referral centres in the Netherlands and Belgium. Those with symptomatic CNS abnormalities or on neurotropic medication, including stimulants, were excluded. Eligible patients were randomly assigned (1:1) via a computer-generated, permuted-block list to simvastatin (10 mg per day in month 1, 20 mg per day in month 2, and 20-40 mg per day in months 3-12) or placebo for 12 months. Investigators, participants, and parents were masked to treatment assignment. Primary outcome measures were full-scale intelligence (Wechsler intelligence scale for children), attention problems (child behaviour checklist, parent-rated [CBCL]), and internalising behavioural problems (CBCL). We did intention-to-treat analyses (of all patients who had outcome data) using linear regression of the 12 month outcome scores, adjusted for baseline performance. This trial is registered with the Netherlands Trial Register, number NTR2150. FINDINGS: We randomly assigned 84 children to a treatment group (43 to simvastatin, 41 to placebo) between March 9, 2010, and March 6, 2012. We did not assess outcomes in two patients in the placebo group because they needed additional drug therapy. Simvastatin for 12 months had no effect on full-scale intelligence (treatment effect compared with placebo -1·3 IQ points [95% CI -3·8 to 1·3]; p=0·33), attention problems (-1·6 T-score points [-4·3 to 1·0]; p=0·23), and internalising behavioural problems (-0·1 T-score points [-3·3 to 3·1]; p=0·96). 38 (88%) of 43 patients on simvastatin and 39 (95%) of 41 patients on placebo reported adverse events, which were serious in two and four patients, respectively. INTERPRETATION: 12 month simvastatin treatment did not ameliorate cognitive deficits or behavioural problems in children with neurofibromatosis type 1. The use of 20-40 mg simvastatin per day for cognitive enhancement in children with neurofibromatosis type 1 is not recommended. FUNDING: The Netherlands Organization for Health Research and Development (ZonMw), Research Foundation Flanders (FWO-Vlaanderen), Marguerite-Marie Delacroix Foundation, and the Dutch Neurofibromatosis Association (NFVN).

Pervasive developmental disorders in Prader-Willi syndrome: the Leuven experience in 59 subjects and controls.

In the present study we investigated the co-morbidity of pervasive developmental disorder (PDD) in 59 Prader-Willi syndrome (PWS) individuals and in 59 non-specific mentally retarded controls, matched for IQ, gender, and age. The 'Pervasive Developmental Disorder Mentally Retardation Scale' (PDD-MRScale), a screening questionnaire based on the DSM-III-R criteria for PDD, has been applied in the PWS group and in the control group. Results of the present study revealed a striking autistic-like behavioral phenotype in the majority of the PWS individuals, particularly deficits in the quality of language and communication and of imagination and interests. This intersection with autistic symptomatology is an important addition to the behavioral phenotype in PWS persons. A first approach to delineate subtypes of autistic symptomalogy among PWS persons was performed. Nineteen percent of the PWS group did meet the full diagnostic DSM-III-R criteria for PDD in comparison with 15% in the control group. Results revealed that a higher IQ in PWS does not protect to develop genuine PDD and that uniparental disomy/imprinting mutation as genetic origin seems to be an additional risk factor for developing genuine PDD. The results of the present study suggest the importance of reconsidering the commonly recognized obsessive-compulsive like behavior in PWS persons within the broader spectrum of autism disorders.

Atypical presentation of the Prader-Willi syndrome. Mosaic trisomy 15?

We report a female with Prader-Willi syndrome and hemihypertrophy. We discuss the possibility of an undetected mosaicism for trisomy 15 explaining this unusual feature.