Children as young as 11 have been treated for drug and alcohol problems in Kirklees.
Shocking figures for local authorities across the UK have revealed youngsters still at primary school have fallen foul of booze and illegal drugs.
Charities have called for improved drugs education in schools after an investigation by the Press Association revealed primary school children are being flagged as at risk of becoming addicts.
One area in Scotland said it had treated a child that was just four-years-old.
Calderdale Council was also one of the few authorities with a 10-year-old child on its drug and alcohol treatment books.
Elsewhere, eight-year-olds had been referred to services in Waltham Forest and East Ayrshire, while nine-year-olds had been referred in Herefordshire, Liverpool, Oxfordshire, Rutland, the Scottish Borders and West Berkshire.
Some 366 children aged 12 or under were referred for treatment in 2012/13 in England, according to the most recent figures from Public Health England, compared with 433 in 2011/12.
A referral can mean the child is vulnerable to drug and alcohol misuse through exposure from a parent or other relative, or could have started abusing substances themselves.
Children are most commonly referred for treatment by education providers or youth offending teams.
More than half of under-13s - 59% - received treatment for cannabis misuse, while a third were treated for alcohol misuse. A small number abused solvents.
Treatment experts said the most common reason for children to come into contact with drugs and alcohol is through their parents and preventative work is key to heading off misuse among youngsters.
The Government has defended the old and new curriculum, adding that all pupils should be taught abut how drugs and other substances can be harmful to the body.
Andrew Brown, director of programmes at charity Mentor UK, which works to protect children from drug and alcohol misuse, said he was shocked at the findings of the Press Association investigation.
Mr Brown, a member of the Supervisory Board of the European Society for Prevention Research, said: “We think it is vital that alcohol and drug education improve. Our own survey of teachers suggests that at the moment delivery is inconsistent, and that the norm is to timetable only one or two sessions a year.
“This may sound sufficient, but evidence would suggest that longer programmes that systematically build skills and values are much more likely to prevent young people from coming to harm than one-off lessons.”
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