The Psychology of Addictive Behaviors has published a new, contradictory update to a recent journal article that concluded marijuana was harmless. The newer article reports a review of the statistical methods used in the first piece and concludes that, in direct contradiction to the first study’s conclusion, there are 2.5 times as many incidences of psychotic disorders among marijuana users than among non-users.
For more detailed reading, see the full press release at the SAM website.