Treating children early for anxiety would reduce their risk of developing severe mental problems in later life by 60 per cent, a new study has suggested.

It is estimated that 38.2 per cent - 165 million people - of people in Europe suffers from a mental disorder and that anxiety is the commonest.

The incidence of depression has doubled since the 1970s and the average age at onset has fallen from the mid-twenties to the late teens as adolescents lost their sense of security in a changing world, according to Professor Hans Ulrich Witten, lead author of study of the state of Europe's mental health.

"We screen for dental caries [decay] - why not for anxiety, ... because the potential treatments are so effective?" the Independent quoted him as saying.

Anxiety disorders could also be a warning sign of neurodegenerative illnesses, such as Parkinson's disease, Professor Witten said.

Professor David Nutt, head of the department of neuropsychopharmacology at Imperial College, London, said: "If you can get in early you may be able to change the course of the illness so people don't progress on to disability."

The study has been published in the journal European Psychopharmacology.