Biomarker Validation in Motor System Physiology in Attention Deficit Hyperactivity Disorder

Overview

Attention-Deficit/Hyperactivity Disorder (ADHD) is the most commonly diagnosed neurobehavioral disorder in childhood. Children with ADHD struggle in school due to problems with attention and high levels of impulsivity and hyperactivity. They are at substantially increased risk for long-term difficulties into adulthood, including academic underachievement, substance abuse, and criminal behavior. The diagnosis of ADHD, which is based on subjective ratings by parents and teachers, likely results from multiple different, overlapping differences in circuits of the brain responsible for attention and impulse control. However, we do not have any scientific or clinical tests that allow us to understand these circuits. In an effort to improve ADHD outcomes, we have used a technology called Transcranial Magnetic Stimulation (TMS) to identify highly reliable measurements of brain function. We have identified two very promising measures that are abnormal in children with ADHD and, importantly, also predict the severity of ADHD behaviors. The goal of this project is to determine if these two TMS measurements could be used to help better guide ADHD treatment. To do this, we will perform three investigations in 8 to 12 year old children to determine: 1) test-retest reliability; 2) pharmacologic responsiveness; and 3) correlations with two domains of function relevant to ADHD: "Cognitive Control" and "Emotional Valence." Through these investigations, we aim to determine whether these two TMS brain measures are reliable and meaningful enough to be used to help improve precision of individually-targeted and effective ADHD treatments.

4.2. NARRATIVE STUDY DESCRIPTION Summary This is a randomized, blinded, placebo-controlled, single-dose crossover study. The objective is to estimate, in a rigorous, unbiased manner, the effect of 10 mg methylphenidate (MPH) on two putative biomarkers of ADHD, measured using Transcranial Magnetic Stimulation (TMS). Two other aims of this larger study, quantifying test-retest reliability and linking TMS biomarkers to RDoC domains of cognitive control and emotional valence, are not directly part of the clinical trial and are fully described in the research strategy. Doctors use observations and subjective rating scales both to diagnose Attention Deficit Hyperactivity Disorder (ADHD) and to make decisions about medical or behavioral treatments. This study addresses the possibility that in children with ADHD, brain-based measurements, or biomarkers, could be useful for diagnosis and treatment decisions. These biomarkers are Short Interval Cortical Inhibition (SICI) and Task-Related Up-Modulation (TRUM). These biomarkers may allow clinicians to identify that a child has a "type" of ADHD which might respond more effectively to treatments that are precisely and individually targeted. Thus it is important to estimate the effects of commonly prescribed treatments on SICI and TRUM. This protocol aims to determine the effects of a single 10 mg dose of MPH, a stimulant medication widely prescribed to treat ADHD, on SICI and TRUM. Assignment of participants For each child with ADHD, participation in the study will consist of three visits. Treatment occurs as a single dose on visits 2 and 3. All participants will receive both placebo and 10 mg MPH. Order will be counterbalanced. Population Sample At the two study sites, Cincinnati Children's Hospital Medical Center (CCHMC) and the Kennedy Krieger Institute (KKI), we will recruit 144 pre-pubescent children, ages 8 years 0 months to 12 years 11 months, with ADHD. We estimate a total of 120 participants will participate in the full study. All recruitment methods will conform to CCHMC Institutional Review Board (IRB) and HIPAA requirements. The study will be approved by the CCHMC Institutional IRB. Children with ADHD will be primarily recruited through community resources, including local chapters of the Children with ADHD (CHADD), local public and private schools, as well as multiple clinics at CCHMC and KKI. Study Flow During the first study visit, participants will provide informed consent. They will then complete diagnostic and psychoeducational testing. The parent/guardian will complete standardized questionnaires and a comprehensive psychiatric diagnostic interview with a trained and research reliable psychology associate under the supervision of a neuropsychologist at each site. At visit 1: if determined to be eligible to continue, visits 2 and 3 will be scheduled at 2-week intervals. At visit 2: participant will undergo pre-dose TMS for measures of SICI and TRUM, receive either MPH or placebo, then undergo post-dose TMS. At visit 3: participant will undergo pre-dose TMS measures of SICI and TRUM (test/re-test assessment), receive the opposite treatment of either MPH or placebo, then undergo post-dose TMS. Intervention - MPH versus Placebo Procedures The MPH and the placebo will be prepared by the study pharmacy at each site so that they appear identical. Neither the child, the parent, nor the investigators will know which treatment is given. The study pharmacy will randomize children into two groups, without disclosing this information to the researchers or participants. Group 1 will receive MPH on the first treatment visit (visit 2 of the study) and placebo the second. Group 2 will receive placebo on the first treatment visit and MPH the second. Note: for comparison and validation of the study measures, 70 children who are typically developing and do not have ADHD will also be enrolled. These control participants will not receive methylphenidate or placebo, however.