A KAIST research team led by Professors Eunjoon Kim and Changwon Kang of the Department of Biological Sciences has determined the genetic and neurological cause of Attention Deficit Hyperactivity Disorder (ADHD): a deficiency of the neurotransmitter GIT1.

Around 5% of all children attending school worldwide are known to suffer from ADHD. They typically exhibit abnormally hyperactive and overimpulsive behavior which disappears in adulthood.

Through biostatistical comparison between the gene types of ADHD-affected and normal children, the team determined that the GIT1 gene in children with ADHD exhibited a single nucleotide mutation. This apparently results in the relative lack of GIT1 in such children.

The team has also backed up its hypothesis with tests on laboratory mice. According to neurological and behavioral analysis of mice that had their GIT1 gene disabled, the animals exhibited similar symptoms to ADHD children.

GIT1-deficient mice, similar to ADHD-affected humans, display hyperactivity, low learning capabilities and abnormal brainwave activity. These mice also corrected their behavior when administered drugs that alleviate the symptoms of ADHD.

Also, similarly to humans, mice that showed signs of ADHD at 2 months of age showed normal behavior when they reached 7 months, around 20 to 30 years old in human terms. “There needs to be a balance of neural stimulation and depression, but GIT1-deficient individuals have a comparative dearth of depressant mechanisms and thus are unable to contain their hyperactivity” Professor Eunjoon Kim explained. “This research has opened new horizons in the development of ADHD treatment” Professor Changwon Kang commented. “GIT1-deficient mice can effectively be used as model organisms in this area.”

The results were published in the online version of Nature Medicine, one of the top biomedical journals in the world. Its importance has also been noted by various newspapers worldwide.

The research was an effective collaboration of many experts from various academic areas such as physiology, genetics, neurogenetics and pediatric psychology. The individuals involved include Professor Daesoo Kim of the Department of Biological Sciences, Professor Jaeseung Jeong of the Department of Bio and Brain Engineering and many others.

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