Cause

• An exact cause of ADHD has not been found, but researchers believe inherited traits and environmental factors play a part in its development.
  
  

Brain Function

• The brain of a person with ADHD is less active in the sections that control attention and activity.
  
  

Heredity

• ADHD can be inherited. One out of every 4 children with attention deficit hyperactivity disorder also has a relative with the disorder.
  
  

Environment

• Toxins in the environment have been linked to the development of ADHD. These environmental factors include being exposed to lead used in the paint and pipes of old buildings.
  
  

Maternity

• Pregnant women who drink alcohol, use drugs or smoke tobacco increase their risk of having a child with ADHD. Being exposed to industrial chemicals while pregnant also has been linked to ADHD.
  
  

Risks

• Risk factors for ADHD include mood disorders, premature birth, having a family history of the condition, hyperthyroidism or a learning disability.