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What do we Know about the Genetics of Attention Deficit Disorder?

written by: jamesj • edited by: Emma Lloyd • updated: 12/18/2010

Studies show that genetics play a considerable role in the incidence and development of ADHD. Attention deficit disorder genetics are the main focus of current medical studies and the results could help with diagnosis and treatment.

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    Causes of ADHD

    There is much debate about ADHD and whether it is real. It is generally held in medical circles, that ADHD is genetic or hereditary in nature. So what do we know about the attention deficit disorder genetics?

    Studies continue to try to identify which genes are responsible for the development of ADHD. Scientists believe the study of attention deficit disorder genetics could hold the key to future treatment.

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    Family studies

    A study led by Dr. Joseph Biederman and the Massachusetts General Hospital found a definite relationship between family members and ADHD. Their study determined that if a child has ADHD, then someone else in the immediate family having the condition is five times more likely than among the general population. Their study also considered adoption, and found that children resembled their biological parents in regards to ADHD more so than their adoptive parents.

    Twins have also been studied. Dr. Florence Levy and her colleagues studied 1,938 families with twins and siblings in Australia and found that 82 percent of identical twins shared the condition, while 38 percent of non-identical twins shared the condition. This has increased interest in attention deficit disorder genetics among medical professionals.

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    Other causes

    Research has also delved into other possible causes of ADHD. Brain injury, tumors, disease and exposure to toxic substances can cause problems with inattention or the regulation of motor activity. At times this can result in a diagnosis of ADHD, but studies have shown that these results are atypical. While some people do develop conditions similar to ADHD after an illness or injury, most do not.

    Studies have also found no correlation between ADHD and diet, hormones, parenting, television and video games.

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    Areas affected

    Scientists agree that the frontal area of the brain is the area most affected by ADHD and that is the region that controls behavior, memory, thinking, planning and organizing, which are affected by ADHD. The problem lies in transmittal of information to the frontal area of the brain, studies have shown.

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    Chemicals

    Research is also showing people with ADHD have a lower than normal level of chemical Dopamine. Adults with ADHD tend to have lower dopamine and the function of it in the body is reduced. This is a chemical that helps transmit information to the frontal areas of the brain, which controls a person's reactions in various situations.

    Stimulants such as Ritalin and Adderall help increase the amount of dopamine, and have been shown to have positive results. Drugs like nicotine and cocaine also temporarily increase the amount of dopamine. The Website WebMD postulates that this could be a reason that people with ADHD are more likely to abuse substances such as nicotine and cocaine.