Professor Neil McKeganey of Glasgow University, who advises the Government on drug prevention strategies, says that sensitive information about parents and other family members known to have a drugs problem should be used to identify children at risk.
The call comes in the wake of the largest ever survey in the UK of illegal pre-teen drug use, which suggests that as many as one in 10 of Scotland's 11 and 12-year-olds have already started to use drugs.
The research, by the Centre for Drug Misuse at Glasgow University under the direction of Professor McKeganey, found that children as young as 11 are taking hard drugs such as heroin, cocaine and amphetamines.
In most cases the drug involved is cannabis, but a quarter had consumed magic mushrooms, 8 per cent cocaine and 6 per cent heroin. More than half of drug takers claimed to have sampled more than one illegal substance.
The alarming findings follow studies among older children which suggest that by the age of 15 more than half have been offered drugs and more than a third have tried them. Professor McKeganey's research suggests not only that drug abuse is spreading to younger age-groups but that it affects all social classes.
The survey of 930 children, aged 11 and 12, was carried out last year across 22 schools throughout Scotland. One of the key findings is that pupils who had started to use illegal drugs were far more likely to have someone in their family who was using illegal drugs. Sixty per cent had a drug user in their family compared with only 12 per cent of the other children in the survey. In most cases the relative was an older brother or sister, but in some cases one or both parents were involved.
Writing in today's TES Scotland, Professor McKeganey warns that drugs education programmes are failing the most vulnerable children by not identifying them early. "By targeting attention on high-risk pupils one stands a better chance of reducing the development of patterns of drug misuse in later life," he says.
Professor McKeganey, a member of the prevention working group of the Advisory Council on the Misuse of Drugs, says that setting up a register, similar to the one which already exists for children at risk from physical or sexual abuse, would enable teachers to work much more effectively with children at risk. "Illegal drug use at this young age is no less pernicious nor the potential consequences any less tragic," he says.
The research also shows that 11 and 12-year-olds who have started to take drugs are far more likely to have started smoking (79 per cent) than non-drug takers (18.5 per cent) and drinking alcohol (91 per cent, compared with 38 per cent).
Pupils who used drugs had been drunk on an average 35 days in the past 12 months compared with 8 per cent of non-drug users.
Analysis, page 21