Causes and Brain Chemistry

Topics in this section:

• Pathophysiology (Brain Differences in AD/HD)
• PAB Statement on Environmental Factors and AD/HD

Although precise causes have not yet been identified, there is little question that heredity makes the largest contribution to the expression of the disorder in the population.

In instances where heredity does not seem to be a factor, difficulties during pregnancy, prenatal exposure to alcohol and tobacco, premature delivery, significantly low birth weight, excessively high body lead levels, and postnatal injury to the prefrontal regions of the brain have all been found to contribute to the risk for AD/HD to varying degrees.

Research does not support the popularly held views that AD/HD arises from excessive sugar intake, food additives, excessive viewing of television, poor child management by parents, or social and environmental factors such as poverty or family chaos.

Other Web Sites:

• Brain Basics: Know Your Brain
  A primer on the brain and brain anatomy for non-scientists, compiled by the National Institute of Neurological Disorders and Stroke.
• Genetics of AD/HD
  The National Institutes of Health tracks and compiles studies on the genetics of AD/HD and other disorders in a database called Online Mendelian Inheritance in Man.