Delay Discounting in Children with ADHD: Neuroimaging and Behavioral Correlates

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DESCRIPTION (provided by applicant): My long-term career goal is to establish a research program to improve treatments for ADHD, with an emphasis on doing so through improved understanding of alterations in cognition and motivation in children with ADHD. This program of research has the potential to inform our understanding of the brain basis of ADHD and to improve outcomes for individuals diagnosed with this chronic disorder. As a clinical psychologist, my graduate training focused primarily on the examination of cognitive and behavioral mechanisms of effective treatments for ADHD (i.e., behavioral therapy and stimulant medication). This led to my interest in the interaction of cognitive and motivational systems in the brain, forming the basis for my dissertation which incorporated neurophysiologic and behavioral measures to study self-regulation. My current position as a postdoctoral fellow has extended my prior training through examination of brain-behavior relationships. As my research interests have developed, I have recognized the need to obtain additional training in neuroimaging to allow for a more comprehensive examination of cognition and motivation, and their interaction. This will ultimately enable me to achieve my long-term career goal to establish an independent career in patient- oriented research. On July 1, 2013, I will be appointed as Faculty at Kennedy Krieger Institute and Instructor in the Department of Psychiatry at Johns Hopkins University School of Medicine. The K23 mechanism will enable me to focus 100% of my time and effort to develop a career as an independent clinical researcher. The Kennedy Krieger Institute and Johns Hopkins University have world-class Psychology, Neuroscience, Biomedical Engineering, Biostatistics, and clinical departments that provide an excellent environment to facilitate my development as an independent investigator studying brain-behavior relationships in ADHD and other neurodevelopmental disorders. The Laboratory for Neurocognitive and Imaging Research (LNIR) is uniquely equipped to support my needs. Under the mentorship of Stewart Mostofsky, M.D. (LNIR Director, primary mentor) and Mark Mahone, Ph.D., ABBP (Department of Neuropsychology, Director, co-mentor), as well as several consultants with expertise in neuroimaging, biostatistics, and behavioral psychology, I will have exceptional intellectual resources to achieve these training objectives and implement the proposed research plan. The cumulative experiences laid out in my training plan will provide the foundation for an independent research program with the goal of receiving an R01 prior to the end of the K23 award. My training objectives are intended to address critical gaps in my knowledge to prepare me for an independent research career. Specifically, I plan to 1) gain knowledge of neuroscience and neuroimaging methods and applications in pediatric populations; 2) obtain training in the examination of brain-behavior relationships; 3) obtain training in statistics and programming and their application to neuroimaging data; 4) improve research collaboration, scientific writing, and presentation skills; and 5) obtain additional trainng in the responsible conduct of research. I will accomplish these training objectives through coursework, guidance from my mentors and consultants with expertise in particular components of my training plan, completion of my research project, and attendance at relevant seminars, workshops, and conferences. The research project I have proposed in this application is the first study to examine the cognitive, neural, and behavioral mechanisms of delay discounting, or impulsive choice, in children with ADHD using a multi-method neuroimaging and behavioral approach. Models of ADHD have emphasized both alterations in reward processing and impairments in cognitive control functions (e.g., attention regulation and working memory), as well as the interaction between these motivational and cognitive processes. In particular, dysfunctional reward signaling consisting of an aversion to delay and a strong preference for smaller, immediate rewards over larger, delayed rewards, a bias referred to as delay discounting, is thought to contribute to the behavioral dysregulation which characterizes ADHD. However, the ADHD literature has been plagued by inconsistent methods complicating interpretation of results. In addition, the relative contributions of alterations in reward processng and cognitive control to increased delay discounting, as well as the neural mechanisms underlying this behavior, are not well understood, particularly in children. Therefore, my study will employ structural and functional brain connectivity to examine the contributions between reward valuation and cognitive control functions to delay discounting in children with ADHD. The findings from this study will contribute to improved understanding of the behavior dysregulation which characterizes ADHD, and more generally impulsive behavior, with the ultimate goal of improving the identification of and outcomes for individuals with this heterogeneous disorder.