Visuoperceptual processing in children with neurofibromatosis type 1: True deficit or artefact?

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.

Neuropsychological factors associated with performance on the rey-osterrieth complex figure test in children with neurofibromatosis type 1

Children with neurofibromatosis type 1 (NF1) are at considerable risk for cognitive difficulties, including visuospatial deficits and executive dysfunction. This study aimed to (1) assess the overall performance of children with NF1 on the Rey-Osterrieth Complex Figure Test (RCFT) compared to unaffected siblings and (2) examine neuropsychological predictors of RCFT performance in children with NF1. A retrospective clinical audit was performed on neuropsychological records from a multidisciplinary NF1 Clinic in Australia. We searched for children that had completed an assessment between 2000 and 2015 which included the RCFT and other neuropsychological outcomes in this study. These included the Wechsler Intelligence Scale for Children, Judgment of Line Orientation (JLO), Tower of London test, Conners ADHD Scales, and the Behavioral Rating Inventory of Executive Function (BRIEF). The study population consisted of 191 children with NF1 aged 6-16 years, and 55 unaffected siblings recruited from a separate study. Results revealed that 62% of children with NF1 performed at or below the first percentile on the RCFT copy, which was significantly worse than their unaffected siblings. Visuospatial skills, parent-rated executive abilities, ADHD symptoms, and intellectual skills all predicted poorer performance on the RCFT copy, however the best fitting multiple regression model only contained the JLO, BRIEF Metacognition Index, and chronological age. The JLO emerged as the strongest predictor of RCFT performance. This study provides evidence that visuospatial deficits are a key driver of reduced RCFT performance in NF1 and that executive skills as well as a younger age are also independent predictors of RCFT performance.

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.

Visual-processing deficits in children with neurofibromatosis type 1: A clinical marker of reading difficulties

Today's estimates indicate that nearly 50% of children with Neurofibromatosis type 1 (NF1) suffer from reading disabilities, with a high impact on their academic achievement. In addition to the well-documented importance of phonological skills in reading acquisition and neurodevelopmental disorders, visual-attention processes also appear as important factors in learning to read. The present study aimed at assessing the role of visual-processing dysfunction in the high prevalence of reading disabilities in NF1 children and providing a useful tool for clinician in the early detection of reading impairment in this neurogenetic disorder. Forty-two children with NF1 and 42 typically developing children (TD) participated in the study. All were right-handed and did not present intellectual disability or attention deficit hyperactivity disorder. Visual-attention processes were assessed with the Developmental Eye Movement (DEM) test, together with the NF1 children's reading level. NF1 children with and without reading disabilities were then compared. The results showed that visual-processing deficits were highly present among the NF1 children included in our study. Furthermore, poor readers with NF1 presented an increased risk of visual-processing deficits compared to peers. This finding supports the role of visual-processing deficits in the reading difficulties encountered in nearly half of children with NF1. Finally, in NF1 children without intellectual or attention disability, visual-processing deficits emerge as one of the clinical markers of reading disabilities. The study holds important clinical implications both for the identification, by providing a useful screening tool, and the management of reading disabilities in NF1 children.

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.

Visuoperceptual Impairment in Children with NF1: From Early Visual Processing to Procedural Strategies

Visual-spatial impairment has long been considered a hallmark feature of neurofibromatosis type 1 (NF1). No study investigating the cognitive and neuropsychological profile of NF1 used the Rey Complex Figure Test (RCFT) task as the primary measure of visual-perceptual abilities taking into consideration all functions involved including the strategic processing style. We compared 18 children with NF1, 17 siblings (S), and 18 typically developing children (TD) at intelligence scale and RCFT copy, recall, and recognition trials; we also evaluated the copy strategy as a measure of a visual-processing style. Children with NF1 had normal total IQ, with cognitive weaknesses in the perceptual organization and working memory in line with the existing literature. At the RCFT copy, immediate and delay recall scores are significantly lower in NF1 than S and TD, while recognition is in the normal range in all groups. Copy style was poor and less efficient in children with NF1 and correlated to copy and recall ability, but the effect of the group in the RCFT copy and recall remained significantly controlling for strategic approach. The present study confirms visuospatial impairment in children with NF1, due to a deficit in perceptual analysis of shape and their spatial features, in visuomotor integration efficiency and strategies, in recall memory, while recognition memory is preserved. A more configural/holistic style may facilitate both the visual-perceptual and visuomotor ability and the recall process. Visuoperceptual impairment in NF1 seems to be a unified process from early visual processing to higher order functions (planning, strategy, and executive functioning).

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).