Researchers identified more genes in ADHD Attention deficit hyperactivity disorder and shows that there is an overlap between some of the genes and those found in other neuropsychiatric conditions such as Autism Spectrum Disorder (ASD).

Attention Deficit Hyperactive Disorder (ADHD) is one of the most common childhood disorders and can continue through adolescence and adulthood. Symptoms include difficulty staying focused and paying attention, difficulty controlling behavior, and hyperactivity. ASD is a complex developmental disability that causes problems with social interaction and communication. Symptoms usually start before age three and can cause delays or problems in many different skills that develop from infancy to adulthood according to NIH.

The study is published in advance online editions of Science Translational Medicine by a research team, which was led by Dr. Russell Schachar, Senior Scientist and Psychiatrist at SickKids and Professor of Psychiatry at the University of Toronto, and Dr. Stephen Scherer, Senior Scientist at SickKids, Director of The Centre for Applied Genomics at SickKids and the McLaughlin Centre at the University of Toronto.

The researchers used microarrays (gene-chip technology) to study the DNA of 248 unrelated patients with ADHD, searching specifically for Copy Number Variants (CNV), which are insertions or deletions affecting the genes.

Of the 173 children, researchers found 3 had spontaneous CNV's that occur when the parents are not affected and mutations are new to the child. Also, rare CNVs that were inherited from the affected parents were found in 19 of 248 patients.

Researchers found some of the genes that had previously been identified in other neuropsychiatric conditions including ASD. To test the overlap, they tested different group for CNV. Of the new group, 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 finding emphasize that CNVs have a common genetic link in ADHD, ASD and other neuropsychiatric disorders.

"For the first time, we've tested these genetic alterations in ADHD and have a pretty good handle on a couple of decent ADHD candidate genes," says Scherer "This is critical, as it gives us confidence in interpreting our results."

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," says Schachar

This method is perhaps one of the most exciting findings in neuropsychiatric genetics and it is really starting to redefine how we think about neuropsychiatric conditions," said Schachar.

Researcher’s emphasis that whiles the new study was able to observe the link more research is needed to determine the cause.