New-generation anti-depressants such as Prozac which are taken by thousands of Scots are largely a waste of time, research suggests today.

New-generation anti-depressants such as Prozac which are taken by thousands of Scots are largely a waste of time, research suggests today.

A review of clinical trials found some of the most widely prescribed drugs were no more effective than a placebo or dummy pill for patients with mild depression.

Even trials that examined improvement among the severely depressed did not provide evidence of clear clinical benefit, say the researchers.

Dr Tim Kendall, deputy director of the Royal College of Psychiatrists Research Unit, said the findings were "fantastically important".

Almost 9% of the Scottish population over the age of 15 take anti-depressants daily, and use has been growing for more than a decade. The total cost of the medication prescribed in Scotland in 2006-07 was £43.7m.

A group of experts, led by Professor Irving Kirsch, from the department of psychology at Hull University, analysed 47 clinical trials using data released under Freedom of Information rules by the US Food and Drug Administration (FDA).

The researchers looked at a new generation of anti- depressants known as Selective Serotonin Reuptake Inhibitors. Prozac and Efexor, which were among the top five drugs prescribed for depression in Scotland last year, were included in their study of four products along with Seroxat.

They concluded that the overall effect of the new generation of anti-depressants was below the recommended threshold used to determine clinical significance.

Apparently good results for very severely depressed patients, they reported, came from the fact a patient's response to the placebo decreased rather than any notable increase in their response to the treatment.

Mr Kirsch said: "The difference in improvement between patients taking placebos and patients taking anti-depressants is not very great. This means that depressed people can improve without chemical treatments.

"Given these results, there seems little reason to prescribe anti-depressant medication to any but the most severely depressed patients, unless alternative treatments have failed to provide a benefit.

"This study raises serious issues that need to be addressed surrounding drug licensing and how drug trial data is reported."

The paper, Initial Severity and Anti-depressant Benefits: A Meta-Analysis of Data Submitted to the FDA, was published in the journal PLoS (Public Library of Science) Medicine.

Dr Kendall said: "What this shows is that, on the basis of published and unpublished data, at the point at which these drugs were licensed in the US, which employs strict criteria about effectiveness, these drugs are not effective as anti-depressants.

"What they have got is a study of all the published and unpublished data on the three most important anti-depressants we use in the UK ... at the point at which they got licensed. On the basis of that, if you used rigorous criteria for deciding whether these are effective drugs, you come to the conclusion they are not in everyone except those with severe depression." He questioned why drug companies were still allowed to publish trial results selectively.

However, he pointed out trials concentrate on the average response and said some patients would be receiving significant benefits from the treatments.

"Those who are taking them and enjoying benefit, should continue to do so," he said.

Charlie McMillan, director of research, influence and change with the Scottish Association for Mental Health, said: "There has been considerable debate for some time about the effectiveness of antidepressants and we welcome this new research. If this research is accurate, then it becomes even more important for people to be able to access non-pharmaceutical treatments quickly and easily."

A spokesman for Eli Lilly, which makes Prozac, said: "Extensive scientific and medical experience has demonstrated that fluoxetine is an effective anti-depressant.

"Since its discovery in 1972, fluoxetine has become one of the world's most-studied medicines.

"More than 40 million people suffering from depression have been treated with fluoxetine in over 100 countries around the world. Lilly is proud of the difference fluoxetine has made to millions of people living with depression."

Figures from the charity Mind show that 31 million prescriptions were written for anti-depressants in the UK in 2006."