Emerging research has discovered new genetic influences for attention deficit hyperactivity disorder (ADHD). Further, the genes appear to be associated with other neuropsychiatric conditions including autism spectrum disorder (ASD).
The study by University of Toronto researchers is published in the advance online edition of Science Translational Medicine.
Researchers used microarrays (gene-chip technology) to study the DNA of 248 unrelated patients with ADHD. They specifically searched for copy number variants (CNVs), which are insertions or deletions affecting the genes. The CNVs may be inherited or occur spontaneously.
In the study, researchers found spontaneous CNVs in three of the 173 children for whom DNA of both parents were available. Inherited CNVs were found in 19 of 248 patients.
Within the group of inherited CNVs, the researchers found some of the genes that had previously been identified in other neuropsychiatric conditions including ASD.
To explore this overlap, they tested a different group for CNVs. They found that nine of the 349 children in the study, all of whom had previously been diagnosed with ASD, carried CNVs that are related to ADHD and other disorders.
The findings suggest that some CNVs, which play a pivotal role in ADHD, increase risk for ADHD, ASD and other neuropsychiatric disorders.
Most individuals with ADHD also have at least one other condition, such as anxiety, mood, conduct or language disorders. Up to 75 per cent of people with ASD also have attention deficits or hyperactivity.
“A lot of these associated problems probably arise from the fact that they are sharing genetic risk for different conditions,” said neuroscientist and senior author Dr. Russell Schachar.
The research results could be reassuring for clinicians who may see characteristics of different neuropsychiatric conditions in their patients – such as ASD-like social problems in a child with ADHD – but are concerned that they are over-interpreting these traits.
“This research reinforces the notion that their gut observation is correct,” Schachar said.
The finding will help scientists expand their research approach to recognize particular genetic profiles may apply to more than just one clinical disorder.
“These are probably genetic factors that increase the risk for various kinds of neuropsychiatric disorders and it poses a huge challenge to us to figure out what makes an ADHD case, what makes an ASD case,” Schachar said.
“There are lots of different possibilities to explain why some common risks can manifest into different kinds of disorders,” he said, adding that while the new study observed this phenomenon, more research is needed to determine the cause.
Source: University of Toronto