The Children's Society's Jenny Frank: "The long-term effects were unknown"

In the first study of its kind, the Children's Society and the Open University School of Health and Social Welfare found that 70% of former young carers suffered long-term psychological effects, and 40% had mental health problems.

The psychological effects included problems relating to people in a social context and difficulty making friends.

Many miss out on playtime and end up adopting a parental role, which can make it difficult for them to adjust to situations where they are expected to behave like children, such as at school.

Mental health problems range from depression and stress to low self esteem. Half of those interviewed had had some form of counselling.

The Children's Society says isolation is a major problem for the estimated 51,000 young carers in the UK.

A spokeswoman said: "Many feel they have no-one to turn to, or that they are letting people down if they talk to someone."

Some children are wary of seeking help because they fear they or their relatives may be taken into care.

Physical health problems

Researchers questioned 66 former young carers about the effects they thought their childhood experiences had had on them in later life.

Twenty-eight per cent said they suffered physical health problems, such as bad backs due to lifting relatives.

Seventy per cent said their education had been affected. Many had had to miss lessons or had had difficulty doing homework because of caring responsibilities.

This often led to poor exam results and problems finding work in later life.

Several had gone into caring professions because they felt they did not have the qualifications to do any other job.

The group included people aged from 25 to over 70, but most had experienced similar problems.

They had cared for a range of adults, including people with multiple sclerosis, cancer, mental illness, and drug and alcohol problems.

A spokeswoman for the Children's Society said the situation had got a little better in recent years because of charities promoting greater awareness of young carers' situation.

There are around 150 organisations which provide help for young carers. They include mentoring services for young carers and places where they can socialise, share experiences with other carers, and feel young.

Others provide advice and information.

But the spokeswoman said the services offered were "very ad hoc" and needed to be more national.

Ring-fenced money

The Children's Society welcomed the government's recently published strategy for carers, but wanted to see ring-fenced money for young carers.

Ian Sparks, its chief executive, said: "We want to see policies, financial backing and determination to ensure these children are not forgotten and can fulfil their potential by giving them and their families the best possible support and advice."

However, the Carers National Association (CNA), which supports many young carers projects and did its own major survey last year, believes it is more a problem of organisation than of funding.

Its survey found that most young carers are aged between 11 and 15; most are girls and over half live in one-parent families.

Only about one in 10 had been assessed by social services.

The CNA wants to see agencies such as social services and schools working closer together, to refer children for help and give advice and support to the whole family.