Attention deficit/hyperactivity disorder (ADHD) is a disorder diagnosed in childhood in which children demonstrate significant difficulties with attention and/or hyperactivity and impulsivity.
The Center for Disease Control notes that 7 percent of children between the ages of 5 and 17 are diagnosed with the disorder. Although various causes for this disorder have been suggested over the years, the predominant factors are genetics, brain structure and environmental risks.
Genetics
According to the National Institute of Mental Health, research has demonstrated that ADHD tends to run in families. As discussed by Robert Weis in "Introduction to Child and Adolescent Psychology," a child's genes are the strongest predictor of his development of the disorder. Children whose parents or siblings have been diagnosed with the disorder have a much greater likelihood of being diagnosed themselves. Research is striving to detect the specific genes implicated in the disorder. As of 2010, genes related to the dopamine system are thought to play an important role in the regulation of attention and behavior inhibition, and have been implicated in the development of ADHD. However, further research is needed to identify specific genes.
Brain Structure
According to "Introduction to Child and Adolescent Psychology," the prefrontal cortex is used to control executive functioning, which is the ability to take in and process information, shift from one task to another, plan, organize and complete goals. Children with ADHD struggle to do this, suggesting that they have deficits in the functioning of this area of the brain. Another area of the brain that has been implicated is the basal ganglia. This area of the brain is related to executive functioning as it passes information through the brain related to attention, action and memory. Children with ADHD have demonstrated abnormalities and underactivity in portions of the basal ganglia, as well as improvements when using stimulant medications that impact this area of the brain. These findings suggest that deficits in this area are related to the limitations in functioning of children with ADHD.
Environmental Risks
In addition to genetics and brain structure, there are aspects of the environment that can contribute to the development of ADHD. The National Institute of Mental Health indicates that both alcohol use and cigarette smoking during pregnancy have been linked to the development of ADHD. Additionally, exposure to lead has also been found to impact its development. An additional risk during pregnancy is fetal oxygen deprivation, which may impact areas of the brain responsible for executive functioning and inhibiting behaviors.
Other Possible Factors
The National Institute of Mental Health describes two other factors thought to influence the development of ADHD. Refined sugar has been accused of exacerbating the symptoms of ADHD; however, research has shown that children given sugar and sugar substitutes showed no differences in their behavior. Additional research has investigated the idea that food additives like preservatives and artificial coloring lead to increased ADHD activity, but as of 2010 have not yet found if they play a role in ADHD symptoms.
References
- Centers for Disease Control and Prevention: Summary of Health Statistics for U.S. Children
- "Introduction to Abnormal Child and Adolescent Psychology"; Robert Weis; 2008
- National Institute of Mental Health: What Causes ADHD?
