Drug addicts are getting older and more over-40s are dying, health officials have said.
But younger adults are becoming more savvy about the dangers of addiction and the number of young heroin addicts has dropped to its lowest recorded level, the National Treatment Agency for Substance Misuse (NTA) said.
Paul Hayes, the NTA's chief executive, also rejected suggestions that the Government should do a "hand-brake turn" and start legalising or decriminalising drugs.
"Any move towards legalisation would certainly mean an increase in use, particularly in the most problematic drugs," he said. "It isn't (Sir) Richard Branson having an extra spliff that's an issue. It's people who struggle with life in Liverpool and Manchester and the East End of London who are actually going to bear the consequences."
Sir Richard is among high-profile campaigners who have called for changes to the Government's drugs policy.
The warning came as NTA figures showed the over-40s now make up almost a third of the whole treatment population in England, with more than 16,000 starting a new course of treatment in 2011/12. More over-40s are also dying from drug misuse, up to 802 last year from 504 in 2001, the figures showed.
Heroin also remains the biggest problem for drug addicts, with four in five of the 197,110 adults in treatment in England being helped for heroin dependency or for heroin and crack. A total of 96,343 were being treated for heroin dependency while a further 63,199 were being helped for heroin and crack use.
"There's no evidence of swathes of people in their 40s and 50s beginning to use heroin and crack as they get older," Mr Hayes said. "It's a population that began using 20 or 30 years ago."
But Mr Hayes also warned there were "risks ahead", saying: "No-one could have predicted in the 1980s that one of the consequences of the recession would have been mass heroin use. It came from nowhere. Whilst this recession has not produced the same levels of youth unemployment that the 1980s did, youth unemployment, hopelessness among young people, provides fertile territory for the next drugs threat to take hold."
Martin Barnes, chief executive of DrugScope, said the decline in heroin use and dependency among young adults was "perhaps a sign that drug treatment has been turning the tide of the heroin epidemic of the 1980s".