Alex Berenson on cannabis: what the evidence says · JRE #1246

What the evidence says 01 / RECORD

The figure traces to a 2018 study of 240 early-phase psychosis patients treated in Switzerland (Lausanne), which found that among the 82 patients with a cannabis use disorder, 38 (46%, close to but not exactly the "50%" cited) displayed violent behavior over a 36-month follow-up, versus 15% (24/158) of patients without a cannabis use disorder. The study had no matched control group of healthy non-users, and its authors explicitly stated that "the small sample size excludes the generalization of these results" and that the finding is "mainly correlational," noting they could not rule out that inherently violent patients used cannabis to self-medicate rather than cannabis driving the violence. The cohort's mean age was about 24 and 67.5% were male, consistent with Berenson's "20-something men" framing, but that demographic reflects the study's convenience sample, not a population-level rate. Broader meta-analyses since have found a statistical association between cannabis use and violence (odds ratios around 2, and up to roughly 5.8 for heavier cannabis misuse), but researchers describe the evidence as confounded by factors like other substance use, impulsivity, and possible reverse causation, and stop short of establishing that cannabis causes violence. A public letter signed by roughly 100 scholars and clinicians accused Berenson, whose book "Tell Your Children" is built around this argument, of inferring causation from correlation and cherry-picking data. The underlying statistic is approximately accurate to its source study but is presented without the small-sample, no-control-group, and correlational caveats the original researchers themselves attached to it.