New study finds psilocybin coupled with spiritual practice produces durable positive changes

Griffiths et al. 2017 just came out yesterday. It had some impressive results, measured over a 6-month study period:

The study collected data from numerous measures, and many robust between-group differences were found. Here are the effect sizes (Cohen’s d) of some of these differences:

  • Altruism: Comparing LD-SS [low dose, standard support] to HD-SS [high dose, standard support], the effect size was 1.36, which statisticians consider “very large.” Comparing LD-SS to HD-HS [high dose, high support], the effect size was 1.95, considered “very large,” almost “huge.”

  • Trait Forgiveness Scale: Comparing LD-SS to HD-HS, the effect size was 0.55, and comparing LD-SS to HD-HS, the effect size was 0.64. Both are considered “medium” effect sizes.

  • Interpersonal Closeness: Comparing LD-SS to HD-SS, the effect size was 0.82 (considered “large”). No significant difference was found between HD-SS and HD-HS.

  • “How personally meaningful was the experience?” This measure yielded the largest effect size seen in the study, 2.47 (considered “huge”), shown between the LD-SS and HD-HS conditions.

On the Revised NEO Personality Inventory, the HD-HS group showed a significant increase in Openness from baseline to 6 months. No significant between-group differences were found in Openness or the other four NEO scales.

Participants were asked to rate the spiritual significance of their experience in the study. Consistent with the positive changes in various traits, 12% of the LD-SS group, 76% of the HD-SS group, and 96% of the HD-HS group rated their experience as among the top 5 most spiritually significant of their lives. Zero percent, 40%, and 56%, respectively, rated it as the single most spiritually significant.

Summary from this article. We'll probably write more about this after we've had time to digest the study.