People who use cannabis before the age of 18 are more likely to end up with fewer academic qualifications, a study of more than 6000 New Zealanders and Australians has shown.
The research found that those who used cannabis before they were 18 were more likely to drop out of high school, less likely to enter university and less likely to get a university degree.
Cannabis has other negative factors associated with it, such as mental health problems, driving impairment and increased use of other illicit drugs - and all these have a greater impact on females than males.
A 2008 World Health Organisation study found New Zealanders had the second-highest rate of cannabis use in the world, behind the United States, with 42 per cent of Kiwis having tried it. About 27 per cent of under-15s and 62 per cent of under-21s had smoked it.
These findings come across as no surprise to people who say that the drug is often used amongst school kids and that the attention given to alcohol abuse is much more than that given to drug abuse.
"If students have a problem with that, we have got to try to use practices to change their behaviour, and you don't change behaviour by booting kids out of school," Stuff.co.nz quoted Denis Pyatt, Canterbury-West Coast Secondary Principals' Association chairman, as saying.
Students on the other hand couldn't care less. While some believe that use of the drug can have no impact on their studies, others avoid using it during exams.
Health effects include increased risk of respiratory disease, decreased cognitive function and cardiovascular disease later in life.