AIM Motor skill impairment and cognitive dysfunction are commonly reported features of neurofibromatosis type 1 (NF1). We characterized and determined the relationship between motor impairment, gait variables, and cognitive function in children and adolescents with NF1.METHOD Motor function, gait, and neurocognitive abilities were assessed in 46 children and adolescents with NF1 (26 males, 20 females; age range 7-17y; mean age 11y 1mo, SD 3y 2mo). Tests to establish correlations between neurocognitive, motor, and gait variables were performed.RESULTS Compared with normative data, 28/39 of our NF1 cohort demonstrated impaired performance for balance and upper limb coordination and 16/38 for running speed and agility. Gait data revealed a strategy to preserve balance at the expense of velocity, with the unexpected exception of a tendency for reduced base of support. Neurocognitive testing confirmed mean IQ in the low average range (86.0) and deficits in spatial working memory and strategy generation. Significant correlations between a number of neurocognitive measures and motor abilities and gait were identified. The largest associations were between gait width and spatial working memory (r=0.594) and running speed and agility with strategy generation (r=0.549). INTERPRETATIONWe have identified a relationship between balance, running speed and agility, gait, and cognition in children with NF1. Findings suggest a shared abnormal neurodevelopmental process underlying some cognitive and motor abilities in NF1. Results are discussed within the context of evidence highlighting abnormal dopamine-mediated corticostriatal circuitry in NF1.Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic condition with a birth incidence of 1 in 2700 individuals.1 Caused by a mutation in the gene encoding neurofibromin on chromosome 17q11.2, NF1 is characterized by a diverse range of cutaneous, neurological, and neoplastic manifestations, including caf e-au-lait macules, skinfold freckling, neurofibromas, and optic pathway tumours. 2Skeletal anomalies have also been documented, including scoliosis, tibial dysplasia/pseudoarthrosis, and sphenoid wing dysplasia. Neurocognitive impairment is also well documented in children with NF1. 3,4 Although intelligence tends to be only mildly affected, specific impairments on measures of attention, executive function, language, and visual perception are common. Given the frequency and severity of cognitive deficits, it is not surprising that up to 70% of children with NF1 underachieve at school, with formal learning disability estimated to be present in approximately 50% of children. 5There is an emerging body of evidence demonstrating motor impairment as a common feature of NF1 in childhood. 4,6,7 Early research in this area documented problems with manual dexterity, balance, and ball skills, with 32% of children exhibiting severe impairment of coordination skills. Reduced motor competency may contribute to a range of poor outcomes for children with NF1. Gross motor skill impairments, fo...