A dramatic shake-up which bases policy on the need for prevention could save the economy billions of pounds every year

Radical plans to prioritise mental health – putting it on a par with the fight against obesity – will be launched this week by the Government.

For the first time, reducing the toll that mental illness takes on people and the public purse will become the responsibility of every government department.

The new strategy will tackle a gap in policy, which has previously concentrated on improving services for seriously ill people at the expense of the prevention of illness for everyone. Only 0.1 per cent of the total adult mental health budget – £2m – was spent on promoting good mental health in 2007-08.

The focus will be on helping children and young people. Investment in mental health services for children and adolescents has in the past lagged behind adult services, which have seen a 32 per cent rise in spending in the past five years.

Louis Appleby, the Government's mental health tsar, said the change in priorities would benefit the economy, the criminal justice system and the health service: "While specialist services for people with schizophrenia, dementia and other mental health problems are, of course, vital, prevention has got to be better than cure.

"We know there are particular groups such as children [in care] who are particularly vulnerable but this is not just about illness. For the first time we will focus attention on improving everyone's emotional resilience as individuals, families, communities and employers can all benefit from strong mental health."

Mr Appleby said no budgets were recession proof but that the economic arguments "are emphatic and straightforward". He continued: "Like good education, good mental health is a stepping stone for a whole range of positive outcomes in adult life which benefit individuals, the welfare system, the health service and the criminal justice system."

The World Health Organisation rates mental illness as the most debilitating of all conditions, ahead of heart disease and cancer; the economic and social costs of such disorders in England alone were estimated at £77bn a year in 2003.

A coalition of organisations including the Royal College of Psychiatrists, the Local Government Association and the Mental Health Foundation have helped to influence the policy shift. However, they stressed that any move towards promoting mental well-being should not be at the expense of people who already suffer from mental health problems.

Steve Shrub from the NHS Confederation said: "The question is not: can we afford this? The question is: can we afford not to do this? The impact of mental illness on people's lives and the economy makes every other condition look like diddly squat.

"All we are arguing for is that the same logic applied to obesity is applied to mental health. If we wait till people get larger and larger they will get heart disease; if we leave people in vulnerable circumstances and leave mental distress untreated then they are more likely to end up with a serious mental illness. But the payback will not be next week; it is more likely to be in five years."

Robert Westhead, 36, has bipolar affective disorder. He had his first major breakdown at 19 and wishes there had been an opportunity to talk about the emotional pressures and stresses that were building up.

Mr Westhead said: "There was none of the touchy-feely stuff to help us cope with life, and emotions and mental illness were more taboo than being gay. Since then I've spent my whole life hiding my illness from friends, family and colleagues, so if this new policy gets everyone talking about mental well-being, then it will make life much easier for people like me.

"I once confessed to an HR officer that I was depressed and suicidal, which was being made worse by bullying at work, but she said there was nothing she could do to help me. Toxic work environments are not good for anyone's mental health, so I hope this new policy will make it everybody's business."