MONDAY, November 26, 2018 – Millions of American children with ADHD, an attention deficit / hyperactivity disorder, may have a genetic vulnerability to the disease, a new study suggests.
Researchers analyzed data from more than 55,000 people and identified 12 gene regions related to ADHD. These regions are likely to affect the central nervous system, according to the authors of the study. The discovery could help scientists develop new treatments for ADHD affecting more than 9 percent of American children.
"We all carry genetic risk variants for ADHD," explained researcher Anders Borglum, a 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 properties, he said. The researchers also discovered that 44 gene variants involved in ADHD are related to depression, anorexia and insomnia.
"We now understand better why some people develop ADHD and start to understand the underlying biology, paving the way for a new and better treatment of ADHD," added Borglum.
The genetic areas that his team exposed show that this is mainly a brain disorder, Borglum said.
The researchers also found that genes that are linked to ADHD play a role in the interaction of brain cells and also influence the development of speech, the learning and regulation of dopamine, a chemical messenger that carries signals between brain cells.
Yet the vast majority of ADHD genetics are still undiscovered and larger studies will be needed, Borglum said.
Study author Stephen Faraone noted that the team "found 12 of the very many – we do not know how many – probably thousands of genes related to ADHD." Pharaone is professor of psychiatry and behavioral sciences at SUNY Upstate Medical University in Syracuse, N.Y.
The researchers do not expect to discover one, two or even ten genes that each have a dramatic effect on causing ADHD and can be used to diagnose the disorder or to quickly develop a treatment, he said. Most likely, a combination of genes and environmental factors causes ADHD, according to the authors of the study.
Environmental factors may be: being born prematurely and having too little or having to deal with developmental problems, such as fetal alcohol syndrome, Faraone said.
Interestingly enough, he added that, although medications work in the treatment of ADHD, they are not focused on the genes that, according to the researchers, were linked to the disorder. None of the genes affected by the drugs appeared in their analysis of genes that are bound to ADHD, Faraone said.
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 a promising study because it provides further evidence that ADHD is likely to be a hereditary condition." Brown was not involved in the study, but was familiar with the findings.
It has been clear for years that ADHD works in families, he said. These findings are also important because they suggest that certain therapies that are effective for a family member are likely to be effective for other family members who have diagnosed ADHD, he added.
This study is also important because it shows that different mental disorders are probably linked to these genes, although no cause-effect relationship has been demonstrated in the study. This information could help families with prevention and early intervention efforts, Brown said.
Visit the American National Institute of Mental Health for more information about ADHD.
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