Even so, the study adds to the understanding of some of the genetic underpinnings of each disorder, he said.
Physicians who treat kids with ADHD and autism say the findings that there can be shared genetic risk underlying both conditions isn't surprising.
"It is very common for a child with autism, or ASD, to present with restlessness, inattention and impulsiveness, so much so that they merit a secondary diagnosis of ADHD, and they sometimes are treated with ADHD [medications] such as stimulants," Schachar said. "And some kids who come to clinics with ADHD have a lot of problems with social interactions, social understanding, and occasionally some of them are thought to be 'spectrumy.'"
But much remains unknown, including what else happens, either genetically or environmentally, that leads one child to develop ADHD and another to develop ASD.
Children and Adults with Attention Deficit/Hyperactivity Disorder (CHADD) has more on ADHD.
SOURCES: Russell Schachar, M.D., senior scientist and child psychiatrist, Hospital for Sick Children, Toronto, Ontario, Canada; Andrew Adesman, M.D., chief of developmental and behavioral pediatrics, Steven and Alexandra Cohen Children's Medical Center of New York, New Hyde Park, N.Y.; Aug. 10, 2011, Science Translational Medicine
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