The rise in drug-related deaths among those aged over 35 is linked to the upsurge in heroin use in Scotland and across Europe in the 1980s and 1990s, creating thousands of problem drug users.

Dr Roy Robertson, chairman of the National Forum on Drug-Related Deaths, was working as a general practitioner in Edinburgh at the time. He noted that while there were about 250 heroin users in Edinburgh in the late 1970s, by the end of 1980 the figure had risen to 4000, with an even larger population in Glasgow.

"For those of us in practice at the time, it was very visible," he said. "People were injecting this thing called smack because their friends were doing it and didn't know what it was. There was an epidemic of heroin use but also of hepatitis B, hepatitis C and HIV."

Many drug users now in the 40+ age range had chronic HIV, hepatitis C, lung disease and heart disease, he said, though the figures in yesterday's report relate to deaths where drugs were directly implicated or were the potential cause.

Methadone was first prescribed as an opiate substitute in the 1960s in New York and its widespread use in Scotland began in the 1980s.

News that there has been a big rise in the number of drug-related deaths where methadone has been present has inevitably prompted questions about its long-term use.

The latest report reveals that, out of 275 deaths where methadone was present, it was the sole drug in the body in only 14 cases.

The question of how to tackle the problem of users taking illicit drugs on top of methadone remains a vexed one.

Dr Robertson argued that more people should come forward for structured drug treatment programmes featuring methadone, saying that taking it under supervision in that context was very safe, whereas in an unstructured way, in low doses, it was unsafe, as it ran the risk of the drug user seeking illicit top-up doses or taking other drugs.

However, long-time critic Dr Neil McKeganey, of the independently run Centre for Drug Misuse Research, claimed methadone was being prescribed "in the face of continuing con-current drug use" and called for a review of the way it was being prescribed.

For the Scottish Drugs Forum (SDF), the drugs policy and information organisation, methadone is only part of the story. It believes the rise in deaths in those aged over 35 is strongly linked to the mental and physical health impacts of long-term drug use and argues that adequate support for this age group is not always available.

Biba Brand of the SDF said: "What will help reduce drug-related death in Scotland is that people with drug problems have rapid and easy access to high-quality, non-judgemental, client-centred drug treatment and wider social support."

Scotland's drug-related deaths are expected to fall in future, due to smaller numbers of younger people entering into opiate use.