The exact cause of attention deficit hyperactivity disorder (ADHD) is not known. But inherited genetic factors are likely responsible. Ongoing research is focused on identifying genes that cause a person to be susceptible to ADHD.

Using various imaging tests, researchers have been able to observe the brain at work. They have found a possible link between ADHD and:

• Brain structure.
• The function of chemicals in the brain that help regulate attention and activity (dopamine and norepinephrine).
• Differences in function of some of the areas of the brain that affect attention and impulse control.

Also, research shows that a mother's use of cigarettes, alcohol, or other drugs during pregnancy may increase the risk for ADHD. Some studies suggest that exposure to lead may cause symptoms associated with ADHD.¹

Although many parents believe that foods with sugar and food additives make their children more hyperactive, these foods have not been shown to cause ADHD. In a comprehensive review of research, the U.S. National Institutes of Health (NIH) found that restricted diets seemed to help only about 5% of children with ADHD, mostly either young children or children with food allergies.¹ Other research has shown that sugar is not related to ADHD.²

Some people have misconceptions about ADHD, such as that children with ADHD are lazy or dumb. Discuss with a health professional any questions or concerns you have about these issues.