Disruption in brain’s reward system linked to ADHD

Until now, the entire focus on the research and treatment of ADHD patients has been on attention as the disorder is primarily associated with a lack of attention. But recent studies have found that kids with ADHD don’t respond to rewards in the same way that kids who don’t suffer from the disorder do.

Dr. Nora D. Volkow, director of the U.S. National Institute on Drug Abuse and key researcher in the study, said that the new study "found a disruption in the brain's reward/motivation pathway" in people with ADHD.

"We also found that disruption in this area was directly related to the severity of inattention,” she added.

Reduced levels of dopamine linked to ADHD
For the purpose of the study, 53 ADHD adult patients and 44 non-ADHD adults were put to the brain imaging test. All of them had to undergo a sophisticated brain scan called positron emission tomography (PET).

Through this scan, researchers tried to find out how the brains of the subjects handled dopamine, a chemical in the brain essential to normal functioning of the nervous system and a key regulator of mood.

Researchers measured the levels of two dopamine proteins- dopamine receptors and transporters- found in the reward centers of brains of all the chosen adults.

The brain scans showed that as compared to the healthy adults, ADHD patients had lower levels of dopamine receptors and transporters in two areas of the brain, known as the nucleus accumbens and midbrain. These are the two key areas involved in processing sensations of reward and motivation.

Significance of the study’s findings
The study suggests that along with abnormalities related to attention, ADHD also stems out of a lack of motivation, causing severity of inattention and hyperactivity among the children.

The findings of the research would help the teachers to devise more engaging sessions for the ADHD kids so that they feel more motivated to remain interested in various activities.

Professor Katya Rubia, of London's Institute of Psychiatry, said: "This study widens our horizons. It shows that ADHD is not just about abnormalities in the attention systems of the brain, but also abnormalities in the motivation and emotion centres.

"It suggests that teachers need to make sure that school tasks are interesting and exciting, so that children with ADHD are motivated to remain interested."

The study also suggests that people with ADHD may be more prone to drug abuse and obesity owing to lower level of motivation.

Dr. Volkow said, "These deficits in the brain's reward system may help explain clinical symptoms of ADHD, including inattention and reduced motivation, as well as the propensity for complications such as drug abuse and obesity among ADHD patients."

Thus, with this study, the researchers are hoping to break the traditional mindset that ADHD is an outcome of bad parenting and try to convince the parents that it's just a medical condition which needs to be treated with utmost care along with the treatment.

The findings of the study are published in the Journal of the American Medical Association.