Children are being over-diagnosed with attention deficit hyperactivity disorder (ADHD), leading to "unnecessary, possibly harmful medical treatment", according to academics.
Changes to the criteria used to diagnose ADHD mean that children are also at risk of being stigmatised when nothing is wrong with them, a report released this week warns.
The report, published in medical periodical BMJ, points out that there has been a rise in the number of people reported to have ADHD, and a parallel rise in prescriptions for drugs to treat the condition. This is partly down to clinicians getting better at detecting the disorder, it says. But it adds that there is also evidence of children being diagnosed without fulfilling the criteria.
The criteria for diagnosing ADHD are set out in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is used around the world to classify mental disorders.
The researchers point out that definitions of ADHD have been broadened in successive editions of DSM and that the latest version, launched in May 2013, now widens the criteria further by raising the maximum age of onset from 7 to 12.
"These changes are a cause for concern because they increase the risk of confusing ADHD with normal development processes, such as pubertal restlessness and distractability," according to the research team, led by Dr Rae Thomas, a senior research fellow at Bond University in Queensland, Australia.
In order to reduce unnecessary diagnosis - without risking under-treatment of those who really need help - a more conservative approach is needed, the report says.
This strategy involves various stages of care before a diagnosis is made, and is similar to one already being used in the UK. Clinicians would assess behaviour and would try to avoid the term ADHD. They would then move on to counselling and, if problems persisted, refer the child to a paediatrician or psychiatrist for treatment.
The report says that this approach would also help to mitigate the other adverse effects of over-diagnosis, including the potential stigma of labelling children and the cost of medication.
Previous research has found that roughly $320-500 million (#163;200-310 million) is spent annually in the US on ADHD treatments for inappropriately diagnosed children.
There have been warnings in the UK that financial pressure on local authority and medical budgets could be leading to the overprescription of ADHD drugs to children as young as 3, as a result of cuts to counselling and other services.
Figures released last year showed that prescriptions of the drug Ritalin in the UK had quadrupled in little over a decade, from 158,000 in 1999 to more than 661,000 in 2010, although this may have been partly because of a switch from quarterly to more frequent prescriptions.
But identifying and treating children with genuine cases of ADHD is important, according to Dr Thomas. Research shows that children who have the condition often find it hard to make friends, perform less well at school and, as adults, are more likely to be unemployed or involved in crime.
"The broadening of the diagnostic criteria in DSM-5 is likely to increase what is already a significant concern about over-diagnosis," Dr Thomas writes.
"It risks resulting in a diagnosis of ADHD being regarded with scepticism to the harm of those with severe problems who unquestionably need sensitive, skilled specialist help and support."
Andrea Bilbow, chief executive of ADHD charity Addiss, said that a diagnosis gave children in the UK access to support in schools. She did not want a return to a narrower definition of the condition.
"This is just churning over the same old argument, and further stigmatises families who are really struggling," she said. "A better approach is to educate people about what ADHD is. It is not about wild kids: hyperactivity can be part of ADHD, but the rest of it is to do with problems with working memory, regulating emotions or regulating moods."