Effects of hypnosis, mindfulness meditation, and education for chronic pain on substance use in veterans: A supplementary analysis of a randomized clinical trial.

The substance use analyses were exploratory and were put together after the main trial results were known, so the authors themselves say the findings are tentative and need repeating before conclusions can be drawn. Two of the three substances showed no effect at all. The cannabis result rests on a small number of daily users and the confidence intervals are wide, so the size of the effect is very uncertain. Around 21% to 23% of participants did not complete the follow-up assessments, and the authors cannot rule out that people who dropped out differed in ways not captured by baseline use. Only how often people used a substance was recorded, not how much, how strong the craving was, or what problems it caused, so it is unknown whether the programmes affected any of those. People taking more than 120 mg daily morphine equivalent were excluded, so the study says nothing about opioid use in higher-dose patients. Every comparison was against the education group, so the study cannot say how much substance use changed within any single group over time. Participants were mainly white, male, treatment-seeking veterans in a state where recreational cannabis is legal, and people with a confirmed substance use disorder diagnosis were not specifically studied.

The authors state that they identify no conflicts of interest. The paper does not name who funded the trial; the text only notes that the study sponsor approved it.

Do not read this as evidence that meditation or hypnosis treats cannabis use. The substance use analyses were written after the main trial results were known, two of the three substances showed no change at all, and the cannabis finding comes from a small number of daily users with wide confidence intervals. The authors call the finding tentative and say it needs replicating.