What types of children are at higher risk for attention deficit hyperactivity disorder?

A partial list. First, adhd is highly heritable, so having a parent or sibling who has adhd or a family history of adhd is the most common set-up. Then comes prematurity; the smaller the baby, the higher the risk of adhd. Many genetic syndromes are associated with with adhd, giving researchers the opportunity to look at the genes involved with adhd. Less common are brain infections or injuries.
Varies. Risk factors: family history of adhd, premature birth, substance abuse (especially stimulants and alcohol) during pregnancy, smoking during pregnancy, children with complicated deliveries. Adhd also can be a result of expsure to toxins such as lead, mercury, or other heavy metals.