I'm familiar with the findings of acute cognitive effects of cannabis intoxication. I'm not familiar with the Ottawa pre-natal study that you refer to, but I am quite familiar with the literature on the cognitive effects of cannabis.
My sense of the literature is that the effects are generally reversible following cessation of cannabis use and that they vary according to the user's familiarity with cannabis, so that when cannabis is administered to relatively naïve users we see more profound deficits and that with regular users there is tolerance of most of the cognitive effects.
Of course, I'm highly concerned about the productivity of our young people. That is what I have devoted much of my life to fostering.