The number of young people seeking treatment for heroin and crack cocaine addiction in England has fallen dramatically, annual figures suggest.
The National Treatment Agency for Substance Misuse said the figures for 18 to 24-year-olds marked a shift away from the "trainspotting generation".
But there has been a "concerning" rise in young adults seeking treatment for cocaine addiction.
In 2008/09 £800m was spent on national drug treatment services.
The investment in services which includes methadone treatment and specialist counselling has more than tripled in the last decade.
In the past year, there were more than 200,000 adults in structured treatment, mainly for heroin and crack cocaine addiction.
Of those 25,000, or 12% of those in treatment successfully beat their dependency, which the NTA said could take years for many users.
Among the 18 to 24 year olds, the number newly presenting for treatment for heroin and crack has fallen 30% since 2005/06 from around 12,000 to 8,500.
Yet in the over 35s addicted to heroin and crack cocaine - the highly addictive smokeable form of the drug - there has been a 20% increase in those seeking treatment.
The figures also showed the proportion of 18 to 24 year olds presenting to drug treatment with powder cocaine addiction has doubled in the past four years.
There has also been a small rise in treatment for cannabis addiction.
Paul Hayes, NTA chief executive, said heroin and crack addiction in England may have passed the "high-water mark".
"While there are increasing numbers of the older 'trainspotting' generation still entering treatment, more are also coming out the other side free of dependency."
He said young people were now more "savvy" about the dangers of heroin use which has lost the glamour it had in the 1980s.
"The increase in cocaine is a concern," he added.
"These trends give an early warning of the need to be geared up to deal with the treatment needs of the next generation."
He said the rise in people seeking treatment for cocaine use was probably due to its use becoming "more normal" among young people out drinking in pubs and clubs.
Dr Emily Finch, a consultant in addiction in South London, said one of the most positive things about the figures was that waiting lists had virtually disappeared.
"The reduction in heroin and crack use in young people indicates to me we are really getting on top of the problem."
But DrugScope chief executive Martin Barnes, said it was "premature" to say the tide is turning on heroin and crack use in young people particularly at a time of recession and rising unemployment.
He added: "The increase in cocaine-related addiction and changing patterns of drug use among young people presents a challenge to the treatment system, which is primarily geared to treating heroin and crack cocaine users."
A spokesman for Addaction said they had concerns that the drive to cut costs in the public sector will hit drug treatment budgets.
"This would seriously undermine the efforts by the NTA and treatment providers like Addaction to turn people's lives around and give them a second chance."