We've written dozens of these "According to a new report..." pieces whereby we marvel at somebody getting a grant to establish the bloody obvious - but with peer reviewed papers and white coats etc. Anyways, folks who start smoking cannabis at a young age rot their brains - yes, old stonerswho started young are less smart AKA dull bores whose brains have a prediliction for conspiracy theories.
I think anybody who has ever lost a friend to cannabis can testify to that - the spliff ash burn marks on the clothes, incredibly dull conversations, daytime TV addiction. The only thing in which they excel is their near autistic/ encyclopaedic knowledge of 24 hour garages and the art of getting cereal packets through that tiny hole they use at night.
Steve Conner in The Independent reports (edited down) "People who started smoking cannabis as adolescents were found at the age of 38 to be still suffering from a drug habit they had started more than 20 years earlier, scientists said. The study suggests that weekly cannabis use before the age of 18 results in an average decline in IQ score of eight points, which is enough to move someone of average intelligence into a category that is well below average."
However, if you're an old stoner and neutral on cancer, rejoice! There's no point quitting now as you can't reverse the damage by quitting.