Motivation May Be at Root of ADHD

Sept. 9 -- TUESDAY, Sept. 8 (HealthDay News) -- The trouble concentrating that affects people with attention-deficit hyperactivity disorder (ADHD) might be related to motivation, a new study has found.

The motivational problems seen with the condition, which is often associated with children but can persist into adulthood, appear to stem from a reduction in dopamine, an important neurotransmitter in the nervous system that is considered a hallmark of ADHD.

"ADHD is traditionally a disease where people think the disruption is in attention and hyperactivity," said Dr. Nora D. Volkow, director of the U.S. National Institute on Drug Abuse and lead researcher on the study. "So, the whole focus on research and treatment has been on attention -- with kids who cannot pay attention or are hyperactive."

Recent studies have found that children with ADHD don't respond to rewards in the same way as children without ADHD, Volkow said. "In addition to the classic symptoms of inattention and hyperactivity, there is also a disruption in motivations and sensitivity to rewards," she said.

The new study "found a disruption in the brain's reward/motivation pathway" in people with ADHD, Volkow said. "We also found that disruption in this area was directly related to the severity of inattention."

The implication of the finding is that ADHD might begin with disruption in motivation, which in turn leads to inattention and hyperactivity, she said.

Volkow described it as "a disruption in interest."

The finding, reported in the Sept. 9 issue of the Journal of the American Medical Association, could have an impact on treating the condition, she said. "My strategy would be rather than exercising the attention network, let me give an intervention that will make the task much more engaging," she said.

For the study, 53 adults with ADHD underwent positron emission tomography (PET) scans for dopamine markers. The researchers compared the results with PET scans of 44 adults without the condition.