ISD Scotland figures point to a falling trend in the uptake of heroin among drug users in their teens and early twenties, with 23% of new clients aged 15 to 19 who sought help for problem drug use in 2010/11 reporting that they took the class A drug.
This was down by one-third on the previous year, suggesting heroin was becoming less attractive to youngsters more likely to abuse ecstasy and cannabis.
The figures, which were based on data gathered from the 10,813 Scots who received a specialist assessment of their drug use during 2010/11, also show heroin use among under-25s has fallen year-on-year from 51% to 44%. But heroin remained the most common cause of people seeking treatment for addiction.
Dave Liddell, director of the Scottish Drugs Forum, said the figures reflected the ageing "Trainspotting generation" who got hooked in the 1980s recession.
Mr Liddell said: "The challenge with a lot of these people is that they've been addicts for 20 years or more.
"Hopefully we are seeing fewer turn to drugs, but we also know that many of the conditions which drive people into addiction – such as deprivation – are still there."
Roseanna Cunningham, Minister for Community Safety and Legal Affairs, said: "Significantly fewer young people are using illegal drugs. However, we are seeing a cohort of hard-to-reach individuals using drugs for more than a decade."