Never Trust the Media on Pot

A Huffington Post debunking of the suggested marijuana-schizophrenia link that made rounds through the media recently. It does a much better, and more succinct, job than my own personal debunking. I suggested studying links between increasing marijuana use and what would have to be increasing rates of schizophrenia if such a link were true. Blogger Maia Szalavitz took care of that:

Second — and this is where virtually all of the coverage falls flat — if marijuana produces what seems like such a large jump in risk for schizophrenia, have schizophrenia rates increased in line with marijuana use rates? A quick search of Medline shows that this is not the case — in fact, as I noted here earlier, some experts think they may actually have fallen. Around the world, roughly 1% of the population has schizophrenia (and another 2% or so have other psychotic disorders), and this proportion doesn’t seem to change much. It is not correlated with population use rates of marijuana.

Since marijuana use rates have skyrocketed since the 1940’s and 50’s, going from single digit percentages of the population trying it to a peak of some 60% of high school seniors trying it in 1979 (stabilizing thereafter at roughly 50% of each high school class), we would expect to see this trend have some visible effect on the prevalence of schizophrenia and other psychoses.

When cigarette smoking barreled through the population, lung cancer rose in parallel; when smoking rates fell, lung cancer rates fell. This is not the case with marijuana and psychotic disorders; if it were, we’d be seeing an epidemic of psychosis.

And that, friends, is why you never trust the media on pot.