WEDNESDAY, Sept. 29 (HealthDay News) -- Many who suffer from attention-deficit hyperactivity disorder (ADHD) appear to have a genetic abnormality that may predispose them to the condition, British researchers report.
Their finding bolsters the belief that ADHD is not solely a social problem but can have origins in an individual's biology. ADHD affects 3 percent to 5 percent of children in the United States, according to the U.S. National Institute of Mental Health.
"ADHD is a complex disorder, and we have known for quite some time that it has a strong genetic composition," said lead researcher Nigel Williams, a senior lecturer in the department of psychological medicine and neurology at the Cardiff University School of Medicine in England.
"This is directly supported by our results, which provide direct evidence that ADHD is a neurodevelopmental disorder," he said.
The report is published online Sept. 30 in The Lancet.
For the study, Williams' team analyzed DNA from 366 children with ADHD, comparing it with the DNA from 1,047 children without the condition.
Children with ADHD were more likely to have missing or duplicated segments of DNA -- called copy number variations (CNVs) -- than were children without ADHD, the researchers found. This type of genetic variation is more common in those with brain disorders, they noted.
In addition, they reported finding significant overlap between these CNVs and CNVs associated with autism and schizophrenia. Though they are separate conditions, there's some overlap between ADHD and autism in terms of symptoms and learning problems, so the two conditions might share a biological basis, the researchers suggested.
The most striking overlap, they said, was found on a region of chromosome 16 that has been linked to schizophrenia and other major psychiatric disorders and includes a gene that plays a role
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