SYDNEY -- A study in Australia has raised concerns about the frequency attention deficit hyperactivity disorder (ADHD) is diagnosed by family doctors and the type of drugs prescribed for it.

Clinical psychologist Bob Jacobs said about 50,000 Australian children were taking stimulants to combat ADHD.

Another 50,000 had been diagnosed with the condition but were not on mediation.

Jacobs, the author of the report, noted that there was no medical test for ADHD.

"Many of them have very significant behavioral problems," Dr. Jacobs said. "There's no question that many children are very challenging behaviorally both for their parents and their teachers."

Other experts have said that a diagnosis of ADHD was often more acceptable to parents than advice that their children needed more discipline. "It's not minimizing that these children present difficult behavior," DPA quoted Jacobs as saying. "It's just what makes us decide that they have a disease without any evidence."