Cognitive-behavioral phenotype or comorbid disorder? The case of attention-deficit-hyperactivity disorder in neurofibromatosis type 1

An evaluation of computerized attention and executive function measures for use with school age children with neurofibromatosis type 1

The present study investigated the performance of children with neurofibromatosis type 1 on computerized assessments of attention and executive function. Relations to ADHD symptomatology were also examined. Participants included 37 children (20 male) with NF1 (9-13 years; Mage = 11.02). Participants completed the NIH Toolbox Dimensional Change Card Sort, List Sort Working Memory (LSWM), and Flanker tasks, as well as Cogstate Identification and One Back tests. ADHD symptomatology was assessed using the K-SADS. Average performance was significantly different from the normative mean on every measure, except LSWM. The NIH Toolbox Flanker and Cogstate Identification tasks detected the highest proportion of participants with at least mild difficulty, and the Cogstate Identification task detected the highest proportion of participants with severe difficulty. Analyses revealed significant relations with ADHD symptomatology for two NIH toolbox tasks. The various computerized measures of attention and executive function offer different information when working with school age children with NF1. The NIH Flanker may offer the most room for change and offers face validity, which may be beneficial for clinical trials research. However, the LSWM shows most support for relations with behavioral indicators of attention and executive challenges.

Psychometric Properties of Attention Measures in Young Children with Neurofibromatosis Type 1: Preliminary Findings

Children with neurofibromatosis type 1 (NF1) often demonstrate difficulties with attention and executive functioning that can be evident starting at a young age. There has been little research about which measures of attention are most suitable for use with young children with NF1. This pilot study explored several computerized measures of attention, a digits forward task, and parent report measures of attention to compare their reliability, validity, and the degree to which they capture attention difficulty in this population. Participants with NF1 ages 4 to 6 years were seen for one (n=2) or two (n=18) time points. Statistical analyses for evaluating evidence for test-retest reliability, convergent and discriminant validity, practice effects, and identification of difficulties were conducted. Each measure demonstrated relative strengths and weaknesses, and there may not be a “one size fits all” measure for use with young children with NF1. However, the Behavior Rating Inventory of Executive Function Preschool/Second Edition, Conners Early Childhood Inattention/Hyperactivity Scale, and the Conners Kiddie Continuous Performance Test Second Edition generally had the highest reliability and most evidence of validity. More specific recommendations are provided for the appropriate measure to use in clinical and research batteries.

Longitudinal Investigation of Early Motor Development in Neurofibromatosis Type 1

OBJECTIVE

Research indicates that children with neurofibromatosis type 1 (NF1) have weaknesses in fine and gross motor development in early childhood; however, little is known about the stability and developmental trajectory of motor functioning. We investigated (1) whether motor difficulties are evident and stable in the preschool period in children with NF1 and (2) whether there are particular patterns of motor development in this population.

METHODS

Participants with NF1 and a control group of unaffected siblings were enrolled at ages 3-8 years and were assessed yearly. Motor functioning was assessed longitudinally using the Scales of Independent Behavior-Revised Motor Scale and the Differential Ability Scales-II Copying subtest. Wilcoxon sign tests were used to compare motor functioning at 3 or 4 years to 5 or 6 years old for children with NF1 seen during both time periods (N = 27). Linear mixed model growth curve analyses were used to compare trajectories for both children with NF1 (N = 62) and unaffected siblings (N = 37).

RESULTS

Children with NF1 made relative gains in raw scores, but not standard scores, across measures. Growth curve analyses revealed a significant effect of NF1 status on gross motor, fine motor, and copying scores, as well as an age by NF1 status effect on fine and gross motor scores.

CONCLUSIONS

Motor difficulties are evident early in life in children with NF1. Though children with NF1 clearly acquire motor skills over time, they continue to fall behind unaffected siblings, with the gap potentially widening over time. Further implications are discussed.

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.

Attention Deficit Predicts Intellectual Functioning in Children with Neurofibromatosis Type 1

Aims

Attention deficit hyperactivity disorder (ADHD) is one of the most frequent neurocognitive impairments in neurofibromatosis type 1 (NF1) and a well-known risk factor for intellectual dysfunction in general. Since NF1 is per se associated with intellectual difficulties, this comorbidity may be crucial for the cognitive development of affected patients. In our study, we investigated if attention deficits are associated with intellectual functioning in NF1 and if children with NF1 plus ADHD differ in their intellectual and attention profiles from children affected by NF1-only or ADHD only.

Methods

111 children aged between 6 and 12 years (53 NF1 plus ADHD, 28 NF1-only, 30 ADHD-only) performed the German version of the intelligence test WISC-IV and a continuous performance test (T.O.V.A.) to assess attention functions. Parents completed questionnaires about everyday attention and executive functions (Conners 3®, BRIEF).

Results

Children with NF1 plus ADHD showed significantly lower intelligence test scores (full-scale IQ: 89.39 [1.40]) than patients with NF1-only (full-scale IQ: 101.14 [1.98]; p < .001), and intellectual functioning correlated significantly with attention performance in NF1 (p < .001). As compared to NF1-only, attention, and executive functioning were impaired on several dimensions (T.O.V.A., Conners 3® and BRIEF) in NF1 plus ADHD. ADHD-only was associated with significantly higher problem scores regarding hyperactivity/impulsivity and inattention (Conners 3®). NF1-only was associated with inattentiveness when compared to the normative sample of the T.O.V.A.

Conclusion

NF1 is associated with variable attention problems. Severe attention deficits appear to be a risk factor for intellectual dysfunction in NF1, more than NF1 without attention deficit. NF1 plus ADHD presents a specific cognitive profile, which differs from that of NF1 and from neurotypical ADHD.

Attention Deficit Hyperactivity Disorder in Neurofibromatosis Type 1: Evaluation with a Continuous Performance Test

Background and Purpose

The objective of this study was to determine if the MOXO visual- and vocal-distractors-based continuous performance test distinguishes patients with attention deficit hyperactivity disorder (ADHD) and neurofibromatosis type 1 (NF1) from those without NF1.

Methods

Thirty-five patients (16 males; mean age 9.91 years) attending a multidisciplinary NF1 clinic completed the MOXO test. The findings were compared to 532 healthy age-matched standardized control subjects (285 males) without ADHD.

Results

The overall performance in the MOXO text was significantly worse in the NF1 group than in controls (p<0.01), but no group-specific pattern was identified. Impulsivity and hyperactivity were significantly more prominent in males than females (p<0.01). Compared to controls, the NF1 group exhibited significantly more failures to respond to target stimuli in the presence of visual distractors.

Conclusions

MOXO scores are abnormal in patients with NF1, but the test cannot differentiate between NF1 with ADHD characteristics and ADHD. The test highlights sex differences in ADHD characteristics in NF1. Overreactivity to visual distractors may form part of the attention deficit in NF1.

Neurodevelopmental disorders in children with neurofibromatosis type 1

Over the past several decades, neurofibromatosis type 1 (NF1) has become increasingly recognized as a neurodevelopmental disorder conferring increased risk for several important neurodevelopmental problems. In this review, we summarize the specific neurodevelopmental problems encountered in the context of NF1. These include impairments in general cognitive function, deficits in specific cognitive domains such as executive function and visuospatial processing and risk for specific learning disorders, impairments in attention and social skills and the overlap with attention-deficit-hyperactivity disorder and autism spectrum disorder, and the risk of developing other psychiatric conditions including anxiety and depression. Early recognition of these developmental impairments is important for the effective treatment of children with NF1, and further characterization is essential to improve our understanding of how mutations in the NF1 gene create the diversity of clinical neuropsychiatric symptomatology observed in this at-risk population.

Cerebral volumetric abnormalities in Neurofibromatosis type 1: associations with parent ratings of social and attention problems, executive dysfunction, and autistic mannerisms

Background

Neurofibromatosis type 1 (NF1) is a single-gene neurodevelopmental disorder, in which social and cognitive problems are highly prevalent. Several commonly observed central nervous system (CNS) abnormalities in NF1 might underlie these social and cognitive problems. Cerebral volumetric abnormalities are among the most consistently observed CNS abnormalities in NF1. This study investigated whether differences were present between NF1 patients and healthy controls (HC) in volumetric measures of cortical and subcortical brain regions and whether differential associations existed for NF1 patients and HC between the volumetric measures and parent ratings of social skills, attention problems, social problems, autistic mannerisms, and executive dysfunction.

Methods

Fifteen NF1 patients (mean age 12.9 years, SD 2.6) and 18 healthy controls (HC, mean age 13.8 years, SD 3.6) underwent 3 T MRI scanning. Segmentation of cortical gray and white matter, as well as volumetry of subcortical nuclei, was carried out. Voxel-based morphometry was performed to assess cortical gray matter density. Correlations were calculated, for NF1-patients and HC separately, between MRI parameters and scores on selected dimensions of the following behavior rating scales: the Social Skills Rating System, the Child Behavior Checklist, the Social Responsiveness Scale, the Behavior Rating Inventory of Executive Functioning, and the Dysexecutive Questionnaire.

Results

After correction for age, sex, and intracranial volume, larger volumes of all subcortical regions were found in NF1 patients compared to controls. Patients further showed decreased gray matter density in midline regions of the frontal and parietal lobes and larger total white matter volume. Significantly more social and attention problems, more autistic mannerisms, and poorer executive functioning were reported for NF1 patients compared to HC. In NF1 patients, larger left putamen volume and larger total white matter volume were associated with more social problems and poorer executive functioning, larger right amygdala volume with poorer executive functioning and autistic mannerisms, and smaller precentral gyrus gray matter density was associated with more social problems. In controls, only significant negative correlations were observed: larger volumes (and greater gray matter density) were associated with better outcomes.

Conclusions

Widespread volumetric differences between patients and controls were found in cortical and subcortical brain regions. In NF1 patients but not HC, larger volumes were associated with poorer behavior ratings.