Category: ADHD - Child
Impulsivity, typically defined as a preference for immediate rewards over delayed rewards regardless of magnitude of reinforcement (Reynolds, 2006; Winstanley, Eagle, & Robbins, 2006), is one of the defining features of Attention-Deficit Hyperactivity Disorder (ADHD; DSM-5, 2013) as evidenced by the consistently poor performance of children with ADHD on delay of gratification tasks (Patros, Alderson, Kasper, Tarle, Lea, & Hudec, 2016). However, the specific mechanisms that account for impulsivity in ADHD are not entirely understood. Reductions in impulsivity, as measured via rating scales, often occur upon the introduction of a psychostimulant regimen (e.g., methylphenidate). Evidence to date suggests that while methylphenidate (MPH) may improve behavior and executive functions, as assessed using rating scales and behavioral inhibition tasks (Coghill et al., 2013; Klein et al., 1997; MTA 1999, 2004), more limited effects are observed for more basic perceptual functions such as time estimation which has also been proposed as a potential mechanism of greater impulsivity (Rubia, et al., 2003; Tannock, 1995). This suggests that MPH may exert its impact on impulsivity through its effect on systems associated with behavioral control rather than perceptual processes (e.g., temporal estimation). The current study seeks to measure the influence of time perception (i.e., perceptual processes) as well as behavioral inhibition (i.e., cognitive abilities) on delay aversion by examining the relationship among these constructs and evaluating the extent to which MPH exerts its effect on all three mechanisms (i.e., perceptual, cognitive, behavioral).
Thirty-three children diagnosed with ADHD between the ages of 7 and 12 participated in three testing sessions that occurred immediately prior to and during their participation in a summer treatment program for children with ADHD. Following a two-week titration of stimulant medication during the summer treatment program, children were randomly assigned to either immediately begin with three weeks of stimulant or placebo medication, then switch to the alternate for an additional three weeks. (e.g., medicated children were switched to placebo for the final three weeks). All children were tested on placebo and on their optimal dose of MPH following the titration period. The testing sessions included a delay aversion task (Patros, Alderson, Lea, and Tarle, 2015), a temporal estimation task (Toplak and Tannock, 2005), and a Stop Signal Paradigm (Schachar et al, 2000). Data collection is complete with data entry completion scheduled for mid-May. All analyses will be completed prior to ABCT and the implications for the interplay between the theorized underlying processes of impulsivity will be discussed.
Mileini Campez– Graduate Student, Florida International University
Joseph Raiker– Florida International University
Kelcey Little– Florida International University
Elizabeth Gnagy– Florida International University
Andrew Greiner– Florida International University
Erika Coles– Florida International University
William Pelham– Florida International University