Researchers at Brookhaven National Laboratory in New York have been comparing the brain chemistry of adults with and without ADHD. They used positron emission tomography (PET) to scan the brains of 97 people, 53 of whom had ADHD; none of the participants with ADHD had received treatment for their condition. The researchers found that the participants with ADHD had less dopamine receptors and transporters in parts of the brain called the nucleus accumbens and the midbrain. Dopamine is an important regulator of mood and the two parts of the brain affected are part of the limbic system which is responsible for emotions, motivation and reward. People with ADHD are more likely to be obese and take drugs and it could be that in doing this they are consciously, or unconsciously, attempting to compensate for a deficient reward system.
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