ADHD Medicine Affects The Brain's Reward System

Scientists from the University of Copenhagen have developed a model of the brain and studied how ADHD medicines have a direct effect on the brain's reward system, especially in children. This helped them understand and improve the medicine and its doses.

"It has been discussed for years whether treating ADHD with Ritalin and similar drugs affects the reward system to any significant degree, simply because the dosage given to patients is so low. We are the first to show that some components of the dopamine signaling pathways are extremely sensitive to drugs like Ritalin. We have also developed a unified theory to describe the effect of such drugs on the dopamine signal," said Jakob Kisbye Dreyer, postdoctoral candidate at the Department of Neuroscience and Pharmacology, Faculty of Medical and Health Sciences, University of Copenhagen, where the model was developed.

According to a study in 2006 which looked into the effects of the ADHD drugs on the brain said that these drugs target a region of the brain which is linked with attention, which is prefrontal cortex (PFC). "Our work provides pretty important information on the importance of targeting the PFC when treating ADHD. In particular it tells us that if we want to produce new ADHD drugs, we need to target [neurotransmitter] transmission in the PFC," says lead author Craig Berridge, a UW-Madison professor of psychology.

Dopamine is known to change human behaviors. Dopamine is a chemical found in the brain which is released more in certain activities like taking narcotics, having sex, excitement of winning something and eating.

"Control mechanisms in the brain help keep the dopamine signal in balance so we can register the tiny deviations that signal reward and punishment. We discovered while trying to describe these control mechanisms that our model can be used to examine the influence of Ritalin, for example, on the signal. Suddenly we could see that different pathways of the reward system are affected to different degrees by the medicine, and we could calculate at what dosage different parts of the signal would be changed or destroyed," Dreyer said.