Causes and Brain Chemistry
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Research has demonstrated that AD/HD has a very strong neurobiological basis.
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, excessive television viewing, poor child management by parents, or social and environmental factors such as poverty or family chaos. Of course, many things, including these, might aggravate symptoms, especially in certain individuals. But the evidence for such individual aggravating circumstances is not strong enough to conclude that they are primary causes of ADHD. A related problem that has some accumulating evidence is sensitivity to food or additives such as colorings and preservatives. Several controlled double-blind studies suggest that these might be important for a minority of children with ADHD, and a couple of controlled studies suggest a small effect on all children whether or not they have ADHD. Further research on this connection is warranted.
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.
The Dana Foundation
The Dana Foundation is a private philanthropy with principal interests in brain science, immunology, and arts education.