Health Conditions

What causes it?

ADHD is related to brain function, but the true cause is still under investigation. One theory is that ADHD is caused by abnormalities in the anatomy of the brain; specifically in the prefrontal cortex, the part of the brain associated with response inhibition. Another theory involves abnormal levels of certain brain chemicals -- called neurotransmitters -- which are used to help brain cells communicate with each other. The brain chemicals that are thought to be affected in people with ADHD are dopamine, norepinephrine, and serotonin.

Symptoms of ADHD may result because the brain does not produce enough dopamine, which then leads to the impulsive symptoms and the lack of self-control commonly seen in patients with ADHD. It is speculated that if the brain does not produce enough norepinephrine, hyperactivity that is consistent with this condition can result. The final brain chemical that may play a part in ADHD is serotonin. If the child shows signs of aggression, then the brain may be producing too much serotonin.

At this point, the exact cause or causes of ADHD are not known, only theorized. As scientists advance their knowledge of the brain, the understanding of the causes of ADHD is expected to grow substantially.