Attention-Deficit Hyperactivity Disorder (ADHD) | Causes & Risk Factors


What causes ADHD?

People who have ADHD do not make enough chemicals in key areas in the brain that are responsible for organizing thought. Without enough of these chemicals, the organizing centers of the brain don't work well. This causes the symptoms in people who have ADHD. Research shows that ADHD is more common in people who have close relatives with the disorder. Recent research also links smoking and other substance abuse during pregnancy to ADHD. Exposure to environmental toxins, such as lead, can also be a factor.

 Things that don't cause ADHD:

  • Bad parenting (though a disorganized home life and school environment can make symptoms worse)
  • Too much sugar
  • Too little sugar
  • Aspartame (one brand name: NutraSweet)
  • Food allergies or other allergies
  • Lack of vitamins
  • Fluorescent lights
  • Too much TV
  • Video games


Diagnosis and Management of Attention-Deficit/Hyperactivity Disorder in Adults by Robert E. Post, MD, MS, and Stuart L. Kurlansik, PhD (American Family Physician May 01, 2012,

Written by editorial staff

Reviewed/Updated: 02/14
Created: 04/97