University of Illinois at Chicago researchers are comparing two drugs commonly used to treat attention deficit hyperactivity disorder to determine if genetic factors predict which children will respond to either or both drugs.
Attention-deficit/hyperactivity disorder (ADHD) (sometimes referred to as ADD) is thought to be a neurological disorder, always present from childhood, which manifests itself with symptoms such as hyperactivity, forgetfulness, poor impulse control, and distractibility. In neurological pathology, ADHD is currently considered to be a chronic syndrome for which no medical cure is available. ADHD is believed to affect between 3-5% of the United States population, including both children and adults.
Many different medications are used to treat ADHD, including stimulants and non-stimulants, says Dr. Mark Stein, principal investigator of the National Institute of Mental Health-funded study and director of the Hyperactivity, Attention, and Learning Problems Clinic at UIC.
“Unfortunately, clinicians are unable to predict in advance who will respond or not respond to a particular medication,” Stein said.
The study will be conducted in Chicago and New York. Stein and colleagues will enroll 160 children and adolescents between ages 7 and 17 in Chicago. Dr. Jeffrey Newcorn of Mt. Sinai School of Medicine heads the New York site.
Participants will undergo psychiatric evaluations, IQ and achievement tests, a blood test, an electrocardiogram and a physical exam. They will then receive several doses of atomoxetine (a non-stimulant medication), melthylphenidate (a stimulant medication), and a placebo, during a carefully monitored blinded dosing sequence to determine their optimal response to each medication.
During the 12 to 15-week study, researchers will assess the children’s ADHD symptoms, social functioning, problem-solving skills and sleep patterns to determine the efficacy and tolerability of each medication.
Previous research conducted by Stein and colleagues found that children with a variant form of a dopamine transporter gene — a variant known to be associated with ADHD — responded poorly to stimulant medication and had more side effects at lower doses. The new study will test whether patients with this genetic marker respond better to non-stimulant medication.
“At the end of the study we hope to be able to look at a child’s biological characteristics to statistically predict who is more likely to respond to a certain medication and to determine who is more likely not to respond or to have a particular side effect,” Stein said.
“The study provides an idealized standard of care in that the children will be carefully evaluated during their treatment with two different medications, with frequent monitoring that typically does not occur during the normal course of ADHD treatment,” said Stein.
At the end of the trial, participants will be referred back to their primary care provider or given a referral for ongoing treatment with information learned from the study.
Co-investigators at UIC include Drs. Edwin Cook and Elizabeth Charney.