Scientists from Bristol University say teenage marijuana smokers are more likely to go on to harder drugs like cocaine and heroin – even if they only do it occasionally.
Smoking cannabis less than once a week was linked to a greater risk of substance abuse in early adulthood – just like in those who smoke it more than once a week.
A study of more than 5,000 adolescents in England found one-in-five fitted this profile.
And the pattern was also associated with harmful drinking and smoking, said scientists.
The findings published in the Journal of Epidemiology Community Health add to the debate about whether marijuana acts as a ‘gateway’ to other drug use.