Pot smokers might not turn into dopes after all

http://www.nature.com/news/pot-smokers-might-not-turn-into-dopes-after-all-1.12207

Full disclosure: I've spent most of my professional career doing chronic disease research in large human cohorts and clinical experiments and teaching other people how to do it.
My 2c: Observational studies suck in many ways, and they are much harder to interpret than you might think if you've never had the pleasure of doing some, but if enthusiastic THC use was anything like as dangerous for human brains as we already know enthusiastic alcohol, crack cocaine or tobacco use is, there would likely be plenty of strongly suggestive observational evidence by now. Given the difficulties of measuring high level brain function, the weakness of the observed intelligence subscale associations (eg zero family wise error rate control - the challenges of multiple hypothesis testing are not even mentioned), the fact that much of the historical "THC" use studied was likely to have been confounded by the effects of its' combustion with tobacco (cigarettes definitely damage small and large blood vessels in the brain and everywhere else...) and other uncertainties discussed in the above link, I suspect that if THC really is rotting my brain, the effect must be relatively subtle - and dear reader, if you made it this far, you're probably doing pretty well too

However, this kind of beat up sure sells newspapers. For the record, I personally find the picture of an evil mix of soon to be combusted bud and tobacco, chosen by the alco-tobacco-pharmaco-entertainment-complex funded media as the iconic representation of THC use, sadly ignorant and depressing.