I know people who drink who haven't achieved squat either. Your average 14-year-old can tell that this reefer-madness rehash is total BS, they know a heck of a lot more than most adults assume. They will never ever be convinced by something they know is a lie.
i dont' doubt that either but any psychotropic drug whether alcohol or pot or drugs can hot wire or short circuit brain function.......not to say the brain won't compensate but the chemical pathways can be muted or renderd immature by excessive chemical introduction.....