Attention-deficit/hyperactivity disorder, or ADHD, is a common neurobehavioral problem that affects children as well as some adults. Some research suggests that the cause of ADHD is a genetic deficiency of certain neurotransmitters.

The brain is composed of millions of interconnecting nerve cells called neurons. In order for a person to think, move, or feel, these neurons must communicate with one another. They do so by sending and receiving chemical messengers called neurotransmitters.

When a neurotransmitter is released from a neuron, it crosses a gap called a synapse and binds to a receptor on another neuron, thus passing on a signal.

The symptoms of the disorder include impulsiveness, hyperactivity, and an inability to maintain attention.

Neurotransmitters, such as dopamine, help regulate behavior. Without dopamine, neurons in the frontal cortex of the brain, which is responsible for attention, do not communicate properly. There is also evidence that the neuronal receptors that recognize dopamine are dysfunctional in people with ADHD.