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.