Study Finds Deficits in Brain’s Reward System in Individuals With ADHD
Research finds that ADHD may not only be linked to areas in the brain that control attention and hyperactivity, but may also be related to abnormalities in the motivation and emotion centers of the brain. The study, conducted at the Brookhaven National Laboratory and published in the Sept. 9, 2009, issue of the Journal of the American Medical Association, found that individuals with ADHD lack key proteins which allow them to experience a sense of reward and motivation.
“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,” says researcher Nora Volkow, MD.
Studies have already indicated that the neurotransmitter dopamine is disrupted in some pathways of the brain and as a result dopamine is not able to activate certain brain regions of individuals with ADHD as it should. Research has now pinpointed the sites in the brain where this seems to occur. There appears to be lower levels of dopamine receptors and transporters in the accumbens and midbrain regions of those with ADHD. These are two key areas of the brain directly involved in processing motivation and reward. This may explain why focusing on tasks that are tedious, boring or uninteresting is so difficult for children and adults with ADHD.
“This pathway plays a key role in reinforcement, motivation, and in learning how to associate various stimuli with rewards,” explains Dr. Volkow. “Its involvement in ADHD supports the use of interventions to enhance the appeal and relevance of school and work tasks to improve performance.”
Finding ways to address this motivation and reward system deficit will likely improve ADHD symptoms and may potentially prevent the emergence of further negative consequences or secondary conditions. As researcher Gene-Jack Wang, MD, notes: “Other studies from our group suggest that patients who abuse drugs or overeat may be unconsciously attempting to compensate for a deficient reward system by boosting their dopamine levels.” Continuing to understand and explore more productive ways to improve the functioning of this reward system may help reduce the frustrations and challenges children and adults with ADHD experience daily.
Children with ADHD can better excel when they are provided stimulating and engaging learning activities in the classroom. Similarly, adults will be more productive with engaging work activities.
Findings also support the use of stimulant medications to treat ADHD by raising dopamine levels.
Source:
Nora D. Volkow, MD; Gene-Jack Wang, MD; Scott H. Kollins, PhD; Tim L. Wigal, PhD; Jeffrey H. Newcorn, MD; Frank Telang, MD; Joanna S. Fowler, PhD; Wei Zhu, PhD; Jean Logan, PhD; Yeming Ma, PhD; Kith Pradhan, MS; Christopher Wong, MS; James M. Swanson, PhD. Evaluating Dopamine Reward Pathway in ADHD. JAMA. 2009;302(10):1084-1091.
Brookhaven National Laboratory News. Deficits in Brain’s Reward System Observed in ADHD Patients - Low levels of dopamine markers may underlie symptoms; implications for treatment. September 8, 2009.
