Comparing the Brain's Response to Methylphenidate vs. Atomoxetine in Children with ADHD
The most frequently utilized treatment for children with ADHD is medication. The vast majority of children with ADHD who are prescribed medication are prescribed psychostimulant medications.
Several imaging studies have examined the functional neurobehavioral effects of the psychostimulant class of medication and have generally found that these medications increase activation in frontal-striatal regions of the brain. Psychostimulant medications are quite effective and have a relatively mild side effect profile for most children, but in some cases alternative medications may be preferred. In 2002, The FDA approved atomoxetine with an indication for ADHD.
Like the psychostimulants, atomoxetine reduced ADHD symptomatology. Unlike the stimulants, atomoxetine purportedly affects predominantly norepinephrine whereas the psychostimulants affect dopaminergic levels in the brain. Few imaging studies have been conducted to examine how the effects of atomoxetine on brain function may be similar or different from that of the psychostimulants. We propose to study in vivo the effects of stimulant and non-stimulant ADHD medications.
The goals of this pilot study are to:
- demonstrate the feasibility of our planned research protocol in this population,
- to gather initial estimates of effect size, and
- to refine protocol procedures.
In this pilot study, approximately 10 children with ADHD (aged 9-13) will be recruited. Children will be recruited from local pediatrician offices. Children will only be selected if they are ADHD medication-naïve and a decision has been made between the child's physician and the child's family to place the child on either a psychostimulant or atomoxetine to treat ADHD.
After signing consent, an ADHD diagnosis will be confirmed using a structured interview administered to the child's parent. Prior to beginning medication, the child will participate in an fMRI and MEG protocol which involves completing a battery of 4 different tasks over the course of 2 days. After 5-7 weeks of treatment on the medication (prescribed by the child's physician), we will repeat the fMRI and MEG protocol over the course of 2 days. The behavioral paradigm tasks encompass a wide variety of cognitive skills designed to tap brain activation in various brain areas, specifically in the frontal and/or striatal regions. Analyses will focus on examining differential medication effects that may be specific to the cognitive construct being tested or to the area of the brain that is being activated.
While formal hypothesis testing is unlikely given the small size of the sample, we expect to be able to determine signal intensities across the different task conditions and across the medication conditions so that estimates of effect sizes can be determined for a future grant application and a more detailed examination of this topic.
