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.For human beings to successfully update responses to a novel environment of continual change, they must constantly evaluate and select from many alternative actions to achieve a positive outcome in a simulated future context. 1 Executive functions are high-level, top-down neurocognitive processes that facilitate this process, by enabling us to plan, execute, and update behaviour in response to changing environmental demands. Neuroanatomical substrates of executive abilities include neural networks connecting the prefrontal cortex, basal ganglia, anterior cingulate gyrus, and cerebellum via the thalamus. 2 Particularly critical functions of the executive system include working memory, which is the ability to retain task-relevant information in mind, and response inhibition, the ability to suppress a conditioned tendency or habit to make a task-appropriate response. 1 Disruption to these executive abilities affects many aspects of day-to-day living, such as engaging in social interactions, learning in the classroom, participating in sporting activities, and the ability to focus attention. The importance of working memory and response inhibition is highlighted by a broad range of neurological and psychiatric conditions characterized by impairments of executive control, such as attention-deficit-hyperactivity diso...

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Young children with neurofibromatosis type 1 are at elevated risk of preliteracy deficits. The most affected domains are phonological awareness and phonological memory. Letter-sound knowledge is the strongest predictor of conventional literacy (spelling).