The exact cause of Attention Deficit Hyperactivity Disorder (ADHD) is not known. The prevailing theories include genetic and hereditary factors as well as neurobiological conditions.

• What is Attention Deficit Hyperactivity Disorder (ADHD)?
• What are the risk factors and causes of Attention Deficit Hyperactivity Disorder (ADHD)?
• What are the symptoms of Attention Deficit Hyperactivity Disorder (ADHD)?
• How is Attention Deficit Hyperactivity Disorder (ADHD) treated?
• ADHD in Children
  
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The cause of ADHD seems to be neurobiological or genetic. Environmental factors influence the severity of the disorder, but environmental factors do not seem to give rise to the condition by themselves. ADHD research is finding more and more evidence that ADHD does not stem from home environment, but from biological causes.

Possible causes of ADHD disorder that have been studied include:

• Environmental Agents: Studies have shown a possible correlation between the use of cigarettes and alcohol during pregnancy and risk for ADHD. High levels of lead in the bodies of young preschool children are another possible environmental cause of ADHD.
• Traumatic Brain Injury: Children who have been in accidents that resulted in brain injury occasionally show some signs of behavior similar to that of ADHD, but only a small percentage of children with ADHD have been found to have suffered a traumatic brain injury.
• Food Additives and Sugar: Some research suggests that attention disorders are caused by refined sugar or food additives, or that symptoms of ADHD are exacerbated by sugar or food additives. In 1982, the National Institutes of Health held a scientific consensus conference to discuss this issue. It was found that diet restrictions helped about 5 percent of children with ADHD.
• Genetics and Hereditary Factors: ADHD hereditary factors appear to run in families. There are likely to be genetic influences to ADHD. Around 25 percent of close relatives in the families of ADHD children also have ADHD. Twin studies show there is a strong genetic influence to ADHD.
• Brain abnormalities: Some ADHD studies have shown structural differences in the brains of ADHD patients.

Sources:

• Attention Deficit Hyperactivity Disorder, a publication of National Institute for Mental Health (2006).
• Biederman J, Faraone SV, Keenan K, Knee D, Tsuang MF. Family-genetic and psychosocial risk factors in DSM-III attention deficit disorder. Journal of the American Academy of Child and Adolescent Psychiatry, 1990; 29(4): 526-533.

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