Every pound spent on helping teenagers cope with drug and alcohol problems saves the taxpayer up to £8 over a lifetime, economists have said.

A total of £62.2m was spent on treating teenagers who misuse substances in 2008-09, but the combination of short and long-term benefits will lead to savings of between £290m and £522m, the study by Frontier Economics found.

These include an immediate 55-65 per cent reduction in offending by young people receiving treatment, a 40 per cent drop in deaths and hospital admissions, and long-term benefits for education, employment and health.

The immediate benefits alone total £120.1m while the longer-term benefits could top £400m over a lifetime, the study for the Department for Education showed.

Overall, a conservative estimate found that every pound spent on teenager’s drug and alcohol treatment could save between £4.66 and £8.38 over a lifetime, it said.

A record 24,000 young people received drug and alcohol interventions in 2008-09, the vast majority for problems with cannabis or alcohol, the National Treatment Agency said.

Paul Hayes, its chief executive, said: “Heavy use of cannabis or alcohol can lead to exclusion from school, family breakdown and crime.

“For those teenagers who seek help, substance misuse is usually one of a range of problems causing difficulties in their life, which is why treatment services must work with partners in youth services to offer a range of support.

“This research shows their efforts pay dividends for society as well as benefiting individuals, and underlines the importance of maintaining investment at local as well as national level.”

Last year, the government’s drugs strategy showed a shift in focus from reducing the harm caused by drugs to recovery as the most effective route out of dependency, with users who are taking steps to become drug-free offered tailored support for their needs.

Addicts could also be stripped of benefits if they refuse treatment and fail to meet the normal requirements for support.