November 13, 2013

According to the Centers for Disease Control and Prevention (CDC), more than 1 in 10 U.S. school-aged kids have received an Attention Deficit Hyperactivity Disorder, or ADHD, diagnosis. That’s 6.4 million children who struggle with inattentiveness, hyperactivity, and – as Dr. Luis Populin from the University of Wisconsin (UW) studies – impulsive behavior.

“If you say to an impulsive child, ‘Do your homework so you will get a good grade at the end of the quarter,’ that has less appeal than ‘Let’s play baseball this afternoon instead of studying chemistry,’” said Dr. Populin, an associate professor of neuroscience at UW-Madison.

To measure impulsive behavior, Dr. Populin studied rhesus monkeys at the Wisconsin National Primate Research Center who showed signs of ADHD, measuring the effects of methylphenidate (or Ritalin, a common ADHD drug) on their working memory and other aspects of executive functioning.

In the study, monkeys who exhibited calmer behavior learned to wait for a larger, delayed reward, while monkeys who tended to fidget and act nervously always chose the immediate, but smaller incentive. This willingness to take a small reward right away, rather than wait for the larger, delayed reward is called “temporal discounting.”

However, when given doses of methylphenidate, both monkeys chose the delayed reward more frequently, improving the condition of temporal discounting – but perhaps impacting other areas of the brain.

Armed with this information, Dr. Populin hopes to devise a mathematical tool that will help a doctor choose the correct dosage to reduce a child’s impulsive behavior – but not hinder executive function skills.

To continue his research, Dr. Populin was awarded the prestigious Hartwell Individual Biomedical Research Award, which provides research funding for three years. With this funding, Dr. Populin and his team are continuing their study of ADHD, examining kid’s temporal discounting (also known as delay discount and time discounting) while playing computer games.

“We will test temporal discounting with a game that kids don’t see as boring, but is still able to evaluate impulsivity so the doctor can make a faster, more accurate dosage calculations,” said Dr. Populin. “Then everybody benefits.”

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