Attention deficit hyperactivity disorder (ADHD) is a neurobiologic condition whose symptoms are also dependent on the child's environment.
ADHD is now one of the most common and most studied conditions of childhood.
Research to date has shown ADHD may be caused by a number of things:
Brain anatomy and function. A lower level of activity in the parts of the brain that control attention and activity level may be associated with ADHD.
ADHD and the Brain from Understood.org.
Genes and heredity. ADHD frequently runs in families. A child with ADHD has a 1 in 4 chance of having a parent with ADHD. It’s also likely that another close family member, such as a sibling, will also have ADHD. Sometimes, ADHD is diagnosed in a parent
at the same time it is diagnosed in the child.
See Inheriting Mental Disorders.
Significant head injuries may cause ADHD in some cases.
Prematurity increases the risk of developing ADHD.
Prenatal exposures, such as alcohol or nicotine from smoking, increase the risk of developing ADHD.
In very rare cases, toxins in the environment may lead to ADHD. For instance, lead in the body can affect child development and behavior.
Why do so many children have ADHD?
The number of children getting treatment for ADHD has risen. It is not clear whether more children have ADHD or more children are receiving a diagnosis of ADHD. Also, more children with ADHD are getting treatment for a longer period.
Because of more awareness and better ways of diagnosing and treating this disorder, more children are being helped.
It may also be the case that school performance has become more important because of the higher technical demand of many jobs, and ADHD frequently interferes with school functioning.