A major new investigation is being launched in to how to handle the so-called "Trainspotting generation" of heroin addicts as they age and increasingly die.

A new government-backed group has been set up in an attempt to establish the size of the health crisis the country will face as the problem users of the 1980s and 1990s enter late middle age.

The over-35s currently account for nearly two-thirds of drug-related deaths in Scotland, with many children mourning the loss of their parents to Class A substances.

Despite a slight drop in the number of drug deaths last year, experts fear it will rise again.

Now the Scottish Drugs Forum (SDF), backed by the Scottish Government, is researching the grim statistics so that public agencies such as the NHS are better placed to cope with the problem.

Dave Liddell, director of the SDF, said: "Despite only being in their forties, many of the ­Trainspotting Generation have physical, social and mental health problems more commonly associated with people in their sixties and seventies.

"We've 60,000 people with drug problems and although we don't have the complete picture, it's likely that more than half of this group are over 35 years of age."

"Certainly the data around new attenders at drug services now show that nearly half are over 35 years of age.

"Often these clients are re-engaging with services after a break often caused by periods in hospital or in significant relapse into heavier drug use. Many of this group are isolated and living alone, and sadly some are ambivalent as to whether they live or die. Recent drug overdose figures show that 62 per cent were older than 35. Accidental overdose and suicide are sometimes impossible to distinguish."

There were 525 drugs deaths in Scotland in 2013, according to the most recent official figures.

Of these, only 32 were aged under 25, the lowest figure since records began. The average age of a victim is more than 40 for the first time.

The SDF this week holds the biggest drug conference in Scottish history, with the ageing profile of addicts topping its agenda.

It comes amid particular concern that many such addicts drop in and out of services.

Many victims die alone, but have had contact with one public service or another in the months preceding their overdose.

The working group will aim to establish the future scale of geriatric addicts, and see whether they need age-specific services or whether those services already dealing with the elderly could play a role in their care.

Experts have long warned that the surviving addicts of the 1980s - documented in Irvine Welsh's novels such as Trainspotting - need therapy and, in some cases, supervised access to heroin on the health service. Although theoretically legal, this option is being resisted by authorities.

Mr Liddell added: "What we have seen over the years is that the therapeutic relationship is a key starting point to assist people, alongside specific help with their health and social needs.

"Some of the components of a quality service may seem very basic but can be very difficult to deliver- for example we need to ensure is that there is a worker who stands by people over the long-term and doesn't allow them to disappear off the radar.

"There are too many examples of people not being able to comply with the requirements of a service and being discharged. So this vulnerable population are not hard to reach but potentially hard to engage with.

"That's why, with the support of the Scottish Government, SDF are putting in place a working group that will make specific recommendations about how responses can be improved."