Attension defect hyperactivity syndrome of children, what is this?

A neurodevelopmental: Disorder: studies show insufficient circulating Dopamine, a neurochemical, in parts of the brain that inhibit behavior, from changes in structure/function of the Dopamine transporter gene or some of the Dopamine receptor genes. Risk for adhd increased with prenatal exposure to tobacco, alcohol , drugs, & some infections, low birth wt., heredity & various syndromes. See CHADD.org for more info.