Article Review: Bulgheroni, S. et al. (2019). Visuoperceptual impairment in children with NF1: From early visual processing to procedural strategies.

Sarah Watts, MS

WKPIC Doctoral Intern

 

This study utilizes the Rey Complex Figure Task (RFTC) to examine visuoperceptual impairment in a group of children with Neurofibromatosis Type 1 (NF1; N=18; aged 6-17 years) when compared to a group of nonaffected siblings of children with NF1 (S; N=17; aged 6 to 22 years) and a group of typically developing children (TD; N=18; aged 6 to 17 years). The study excluded participants with brain tumors (including optic glioma), with full-scale IQ less than 75, and other developmental disorders including autism spectrum disorder, basic visual impairments, epilepsy, and hydrocephalus.

 

The study utilized the Child Behavior Checklist (CBCL) 6-18 and Conners Rating Scale-Revised to assess for behavioral symptoms of Attention Deficit/Hyperactivity Disorder (ADHD). Cognitive Ability was assessed using the Wechsler Intelligence Scale for Children, Third Edition (WISC-III) Full-Scale (FS), Verbal Comprehension (VC), Perceptual Organization (PO), Freedom from Distractibility (FFD) and Processing Speed (PS). The Meyers & Meyers (1995 version) of the RCFT was used to assess visuoperceptual processing and memory, which included supplemental norms for children and a recognition trial. Accuracy of figure and figure placement was assessed. The investigators also examined “how” participants approached copying the figure (Copy Strategy) on a 4-point scale (1 being most efficient to 4 being least efficient). Tests were administered by two neuropsychologists that were blind to which group the children belonged to.

 

The results of the study, with regards to overall cognitive ability, was consistent with previous research where children with NF1 generally score in the average range for overall cognitive ability but exhibit deficits in visuospatial processing and working memory when compared to typically developing children.

 

The researchers recognized that there are many aspects of cognitive functioning that contribute to scores on the RCFT. Thus, they examined the RCFT in terms of accuracy of shape reproduction and the spatial placement of different elements of the figure. There were no differences found between accuracy scores between groups; however, the NF1 group had more difficulty with spatial placement than did the TD group. The researchers suggested that deficits in the accurate reproduction of shapes would be associated with dysfunction of the ventral cortical pathway and deficits in the spatial placement may be associated with dysfunction in the dorsal cortical pathway.

 

The authors suggest that the finding of this study supports the hypothesis that typically developing children demonstrate more efficient strategies for copying visual information than do children with NF1. When controlling for Copy Strategy, a significant difference remained between NF1 and TD groups for copy and recall suggesting that poor copy strategy does not fully explain the difference in the copy and recall scores.

 

While the authors note that much of the research examining visual memory in children with NF1 did not indicate deficits in visual memory, they make note that studies using RCFT studies showed poorer performance on visual memory in children with NF1 compared to nonaffected children. The authors suggest that this difference may be related to the inherent differences between recall and recognition. The authors neglect to mention the possible implications of confounding variables such as the RCFT’s reliance on visual planning and graphomotor ability.

 

The authors point out the following limitations: (1) the small sample size; (2) the strict exclusion criteria, which includes some conditions that children with NF1 are at an increased risk of having (e.g., brain tumors and neurological conditions); and (3) not directly assessing the association between visual-perceptual abilities and executive functioning. In addition to the aforementioned limitations, there are several issues with the design and execution of the study that may have implications for interpreting the results of the study. First, the authors discount the potential for an association between executive functioning deficits and differences in Copy Strategy due to the lack of correlation between the two. However, the authors did not note that the two measures of executive functioning are parent report measures of behavioral manifestations of problems with executive functioning and are not a direct measure of executive functioning deficits. Thus, it is possible that children with less behaviorally disruptive manifestations of executive functioning deficits may be under-represented by the measure.

In addition, the use of the RCFT as the only measure of visuospatial processing when comparing groups leaves room for the conflation of deficits in other aspects of cognitive functioning (e.g., graphomotor coordination and visual spatial planning) with deficits in visual recall. Thus, conclusions drawn from the results may not be reflective of deficits in visuospatial processing.

 

Another concern with the use of the RCTF recognition task is that the task does not measure memory of the spatial relationship between different aspects of the figure. The authors make the assumption that the child with NF1 is accurately encoding the visual information and is exhibiting deficits in recall. However, the design of the RCTF recognition task does not rule out the possibility that the spatial relationships were not accurately processed and encoded.

 

Directions for future research should include further analysis to determine what role, if any, executive functioning plays in the RFTC copy and recall scores. In addition, this research may have a functional impact on school related accommodations and alterations to teaching strategies and curriculum for children with NF1. For example, children with NF1 may benefit from instruction on strategies for visual organization and instruction that relies less heavily on the visual presentation of educational materials.

 

References:

Bulgheroni, S., Taddei, M., Saletti, V., Esposito, S., Micheli, R., & Riva, D. (2019). Visuoperceptual impairment in children with NF1: From early visual processing to procedural strategies. Behavioural Neurology, 2019. doi: 10.1155/2019/7146168

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