New research investigating adolescent cannabis use and its effect on IQ later in life has been widely covered in the media.
The study, which was based on the a longitudinal study of over 1,000 people born in Dunedin in 1972-3. Researchers found individuals who started using cannabis in adolescence and used it for years afterward showed an average decline in IQ of 8 points when their age 13 and age 38 IQ tests were compared. Ending cannabis use did not appear to reverse the loss either, the researchers found.
However, among people who starting using cannabis after the age of 18 the, IQ decline was not seen.
The study was published today in the journal Proceedings of the National Academy of Sciences.
You can read more about the study, and expert commentary collected by the SMC, here.
Examples of media coverage include:
Otago Daily Times: Cannabis use by teens harmful: study
Newstalk ZB: Findings of groundbreaking cannabis study released
MSN News: Pot use by teens may do permanent damage
3 News: Cannabis use linked to IQ loss
Stuff.co.nz: Early cannabis use hits intelligence: study | Stuff.co.nz
Radio New Zealand: IQ decline seen in early cannabis users