The study, published in the journal Proceedings of the National Academy of Sciences, claims that those who begin smoking cannabis heavily as a teenager have lower IQ scores as adults. More worrying was the finding that this IQ dip appears to be irreversible even if the person quits smoking cannabis as an adult. Alternately, if the person continued the heavy usage into adulthood, the research found that the individuals suffered an eight-point IQ decline on average. The research study tracked 1,000 individuals in New Zealand over the course of their entire lives since birth in 1972 and 1973.
Of course these findings won’t sit well with some scientists and researchers who have done some of their best work while "under the influence" in college or elsewhere, and IQ tests remain a dubious measure of real, applied intelligence. Nevertheless, these latest findings offer food for thought for those looking to keep their brains working at optimum levels at all costs as they chase that next big breakthrough.