MONDAY, November 26, 2018 – Millions of American children with attention deficit / hyperactivity disorder, or ADHD, may have a genetic vulnerability to the disease, a new study suggests.
The researchers analyzed data from more than 55,000 individuals and identified 12 genetic regions related to ADHD. These regions probably affect the central nervous system, the study authors said. The discovery could help scientists develop new treatments for ADHD, which affects more than 9 percent of American children.
"We all have variants of genetic risk for ADHD," explained researcher Anders Borglum, professor of biomedicine at the University of Aarhus in Denmark. "The more we have, the greater our risk of developing ADHD."
Those same genetic areas share a connection with 200 other diseases and traits, he said. The researchers also found that 44 genetic variants involved in ADHD are related to depression, anorexia and insomnia.
"Now we understand better why some people develop ADHD and we begin to know the underlying biology, paving the way to a new and better treatment for ADHD," Borglum added.
The genetic areas that his team discovered show that this is primarily a brain disorder, said Borglum.
The researchers also found that genes that may be related to ADHD have a role in the way that brain cells interact and also affect the development of speech, learning and regulation of dopamine, a chemical messenger that carries signals between the cells of the brain.
Still, the vast majority of ADHD genetics has not yet been discovered and will require more extensive studies, Borglum said.
The study's author, Stephen Faraone, noted that the team "found 12 of the many, we do not know how many, probably thousands of genes related to ADHD." Faraone is a professor of psychiatry and behavioral science at SUNY Upstate Medical University in Syracuse, N.Y.
The researchers do not expect to discover just one, two or even 10 genes, each of which has a dramatic effect on the cause of ADHD and can be used to diagnose the disorder or quickly develop a treatment, he said. Most likely, a combination of genes and environmental factors will trigger ADHD, the study authors said.
Environmental factors may include being born prematurely and having low birth weight or developmental problems, such as fetal alcohol syndrome, Faraone said.
Interestingly, he added, although the drugs work in the treatment of ADHD, they do not point to genes that the researchers found were related to the disease. None of the genes affected by the drugs appeared in their analysis of genes related to ADHD, said Faraone.
The report was published online on November 26 in the journal Nature Genetics.
Ronald Brown, dean of the School of Health Sciences at the University of Nevada in Las Vegas, said: "This is promising research because it provides additional evidence that ADHD is probably a hereditary disorder." Brown did not participate in the study, but was familiar with the findings.
It has been clear for years that ADHD occurs in families, he said. These findings are also important because they suggest that certain effective therapies for a family member are likely to be effective for other members of the family who are diagnosed with ADHD, he added.
This study is also important because it shows that several psychological disorders are likely to be related to these genes, although a cause and effect relationship was not demonstrated in the study. This information could help families with prevention and early intervention efforts, Brown said.
Visit the US National Institute of Mental Health UU For more information about ADHD.
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