"This effect was present even after researchers accounted for the fact that ADHD children with the worst symptoms were most likely to be prescribed the drugs."

"This effect was present even after researchers accounted for the fact that ADHD children with the worst symptoms were most likely to be prescribed the drugs." How do they account for this? "Professor Ian Hickie from the Brain and Mind Research Institute says it's possible that those on medication didn't perform any better because their condition was more serious to begin with." http://www.abc.net.au/pm/content/2010/s2822748.htm http://www.abc.net.au/pm/content/2010/s2822748.htm