What is the physiological basis of AD/HD?

What usually stands behind AD/HD is a genetic tendency to have a "mild chemical imbalance" in the brain, involving mostly the neurotransmitters dopamine, epinephrine, and norepinephrine. Decreased dopamine function in the brain results in slowed "dopaminergic" neurotransmission that leads to a poor utilization of some brain activities. This results in the AD/HD symptoms. Supplementing the brain with missing dopamine, as a result of the use of stimulant medications, may correct this situation.

Dr. Grossmann likes to use a graphic representation to help explain to families and patients the physiological basis of AD/HD.

This is a simplified understanding of the mechanism which is more complicated, involving other neurotransmitters as well, including norepinephrine and serotonin, as well as different areas of the brain which are more involved than others.