Neurobiology and Treatment of Reading Disability in NF1

点击翻译按钮获取中文摘要

Neurofibromatosis Type 1 (NF1), an autosomal dominant neurocutaneous syndrome with an incidence of 1:3000, is caused by a mutation in neurofibromin -- a protein that negatively impacts learning by altering RAS signaling in long term potentiation (LTP). Clinically, NF1 shows four times greater rate of learning disabilities (65%) compared to the general population (15%), including reading disability (RD), resulting in educational impairment. The negative impact on academics makes these learning disabilities, including reading disability, among the most common concerns of parents of children with NF1. In previous research (NS49096), we demonstrated that children with NF-1 with reading difficulty (NF+RD) are able to respond to standard phonologically-based reading tutoring that was originally developed to treat children in the general population with idiopathic reading disability (IRD). Of central importance to this application, another line of research in the mouse model of NF has shown that pharmacological treatment (Lovastatin) reverses learning deficits (Li et al., 2005). The assumed mechanism is that Lovastatin, an HMGCoA reductase inhibitor, upregulates RAS signaling to counteract the negative LTP effects of deficient neurofibromin, thus allowing for better memory formation during learning. This finding has stimulated translational research to assess whether Lovastatin, a medication that the American Academy of Pediatrics to endorses as safe to use in children, can reverse cognitive deficits in humans with NF1. Promising results have been found in studies that, similar to the mouse studies, measure specific cognitive domains or pair Lovastatin with training of the deficient skill. Given that (a) NF+RD benefit from reading tutoring and (b) pharmaceutical benefits appear linked to specific study designs, several next steps are needed to better understand the behavioral and neural mechanisms of cognition in NF1. Specifically, we propose a clinical trial in which we pre-treat the NF+RD children with Lovastatin for the 12 weeks prior to reading tutoring, as compared to NF+RD who receive either reading tutoring or Lovastatin; critically, like animal studies, we will target those who show impaired learning on the specific skill to be taught, i.e., NF+RD will receive reading tutoring. Both behavioral and neurobiological measures are proposed, and changes in functional and structural connectivity are expected to occur with enhanced cognition. In particular, the combination of behavioral and pharmacological intervention is hypothesized to have a synergistic effect producing greater gains in cognition and changes in neurobiology than Lovastatin or tutoring alone. In sum, our overarching goal in this next phase of our research is to capitalize on current findings to elucidate mechanisms of and best treatments for the cognitive deficits in NF1. Such approach could also have a broader applicability for better understanding human learning mechanisms in developmental disorders.