ADHD is the most commonly diagnosed mental health disorder in childhood and is associated with functional impairments across multiple academic and social domains throughout the life span. It has become increasingly clear that there are multiple causes of ADHD and functional outcomes for individuals with ADHD are dependent on a number of factors. Intensive, evidence-based treatments for ADHD (i.e., behavior modification and stimulant medication) are generally effective in reducing symptoms of ADHD, although many individuals with ADHD continue to show both symptoms and functional impairment, despite receiving treatment. Understanding the factors related to which individuals will respond to treatment and how treatments work are crucial to improving the outcomes for individuals with ADHD. Identification of biologically relevant neurobehavioral systems associated with ADHD is central to this research. However, this has proven challenging given the heterogeneity of ADHD and the reliance on behavioral symptoms of inattention, hyperactivity, and impulsivity for diagnostic criteria. Therefore, clarifying the nature of cognitive and motivational deficits implicated in ADHD, as an intermediary between brain function and behavioral symptoms, is an important first step towards the development of innovative new therapies to improve long-term outcomes.
We are examining the cognitive, neural, and behavioral components of a type of impulsive decision-making called delay discounting in children with ADHD. Models of ADHD have emphasized both alterations in reward processing and impairments in executive functions (e.g., attention regulation and working memory), as well as the interaction between these motivational and cognitive processes. In particular, 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 symptoms of ADHD. However, the relative contributions of atypical motivation and executive dysfunction to increased delay discounting, as well as the neural mechanisms underlying this behavior, are not well understood, particularly in children. To this end, we employ a multi-method neuroimaging and behavioral approach, involving neural measures of structural and functional connectivity between brain regions involved in motivation and self-control, and behavioral measures of executive function and preference for immediate reward. 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.