University of London researchers compared prescribing rates between 2000 and 2002 in countries in Europe, South America and North America.

During that period, the UK saw a 68% rise in children being prescribed drugs to stimulate or calm the brain.

The research is published in Archives of Disease in Childhood.

Some common antidepressants were withdrawn from UK paediatric use last year, but the researchers say doctors are likely to move to others.

The team, from the Centre for Paediatric Pharmacy Research at UCL, looked at prescribing of antidepressants, stimulants, antipsychotics, tranquilisers and medications to treat anxiety.

They examined prescription data for children up to 17 in the UK, France, Germany, Spain, Argentina, Brazil, Mexico, Canada and the US.

The information came from an international database (IMS MIDAS), which draws on data from a representative sample of medical practitioners in each country.

It was found children are generally being prescribed more antidepressants and other drugs designed to calm or stimulate the brain.

The highest increase of 68% was recorded in the UK. Many of the prescriptions were for medications used in the treatment of Attention Deficit Hyperactive Disorder.

Significant rises in the number of prescriptions for these drugs were evident in all countries, except Canada and Germany where the increase in prescriptions over the period was just 13%.

Bed-wetting

A second study by researchers at the centre looked at the rise in paediatric antidepressant prescribing to UK children under 18 between 1992 and 2001 using data from the General Practice Research Database.

Almost 25,000 children and adolescents were given 93,000 prescriptions, of which over half (55%) were for the older-style tricyclic antidepressants.

Tricyclics are licensed for the treatment of depression and night time bedwetting. Most of the prescriptions for children under 10 mentioned nocturnal enuresis, and not depression.

Four out of 10 prescriptions were for SSRIs such as Prozac (fluoxetine) and Seroxat (paroxetine)

The rate of antidepressant prescriptions for children rose by 70% in a decade. While the rate for tricyclics fell by 30%, that for SSRIs rose 10-fold from 0.5 children treated out of 1,000 to 4.6.

The researchers say almost half of adolescents with clinical depression had been prescribed tricyclics, despite the fact that these drugs are considered only moderately effective in this age group.

Dr Ian Wong, director of the centre said: "There is an element of better recognition of child and adolescent mental ill health."

Last year, the UK Medicines and Healthcare Products Regulatory Agency recommended most SSRIs should not be given to children.

While Dr Wong says this will impact on prescribing rates, he said doctors would simply use other antidepressant medications because of the lack of availability of other options, such as psychotherapy.

"We will see some sort of fall in prescribing rates, but we can't stop it all.

"Prozac can still be used, so we expect to see a drop but I'm not sure how big. And there are other types of antidepressants that could be used."

Dr Wong said more research was needed into how drugs affected children, rather than using data drawn from adult usage.

Alternatives

Lee Miller, from the charity Young Minds, said the prescribing figures would have changed since the new guidance on SSRIs.

He said: "We need to think about alternatives to medication for children with depression."

But he added: "There isn't enough funding going into providing other therapies for depressed children, such as cognitive or talking therapies.

Paul Burstow, Liberal Democrat health spokesman, said: "While it is good that the existence of mental health problems in children and teenagers is becoming more recognised, it is still disturbing to see such a large increase in prescriptions for children."