Regular use of cannabis during teenage years may come with a long term problem after a new study published in the Proceedings of the National Academy of Sciences revealed that people who used cannabis when they were teenagers suffered from an IQ loss during their adulthood.
The study was conducted by researchers at Duke University, in the US, who followed more than 1,000 people in Dunedin over a period of 25 years. The researchers recorded the IQs of the participants when they were 13 years of age and interviewed them about their cannabis usage when they were 18, 21, 26, 32 and 38 years old.
The researchers found that those who were regular users of cannabis by the age of 18 years had the lowest IQs when they were 38 years old and the fall in IQs was more severe among the participants who continued to use cannabis in their early adulthood.
Stating that the study showed cannabis was not a benign compound as popularly assumed, University of New South Wales School of Psychiatry's Dr Matthew Large said, "You don't get any better information than this. It adds to a growing body of knowledge that cannabis is not an entirely benign compound."