Though far from being an all-out pothead, I occasionally smoke a little smoke and, to the best of my knowledge, have never experienced any ill effects (aside from that way natty brownie I ate on my 18th birthday). I have however heard a ton of nonsense on the subject concerning brain cancer, sterility, mental disorders, and, thanks to one fanatically religious friend, death and damnation. Being a reasonably health-conscious guy, I was wondering, what serious physical or mental effects could smoking marijuana have on me? –Brian, Long Beach, California

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I first wrote about the health implications of pot use in 1985. (Short version: Won’t kill you, but ain’t mother’s milk either.) Since then a staggering amount of research has been done–a search on marijuana in PubMed, the federally funded online medical-journal database, turns up close to 4,000 articles in the last ten years alone. Start reading up on the subject, though, and you quickly realize that however fine the wheels of science may grind, they sure grind exceeding slow. Believe it or not, some of these guys are still arguing over whether weed causes reefer madness. The latest:

Does marijuana cause memory loss, apathy, etc? While these questions haven’t been settled (big surprise), scientific fans of cannabis now put a different spin on them. Getting stoned makes you forgetful? Hey, that’s not a bug, it’s a feature. Biologist Robert Melamede, author of the article cited above, writes, “Cannabinoids control the extinction of painful memories. What a blessing for those suffering from debilitating or life threatening illnesses: cannabinoids may help them to forget their misfortune.” Cannabinoids also regulate nerve sensitivity, preventing early cell death due to overexcitement–in other words, they make cells mellow out much as they do the whole organism.