More preparation therapy linked to bigger depression improvements in psychedelic trials

The question

In trials of psychedelic-assisted therapy for depression, does the amount of talk therapy given around the drug session relate to how much symptoms improve?

What they did

Researchers searched three research databases up to June 16, 2025 for controlled clinical trials in adults with depressive symptoms who received a classic serotonergic psychedelic (such as psilocybin or LSD) alongside preparation sessions before dosing and integration sessions afterward. Of 226 records found, 42 full papers were checked by two independent reviewers and 12 trials met the criteria. The combined sample was 733 participants (365 female, 49.8%; mean age 43.1 years). They pooled the results statistically and then tested whether hours of preparation, hours of integration, number of sessions or overall duration related to outcomes.

What they found

Across the trials, psychedelic-assisted therapy reduced depressive symptoms more than control conditions, with a large pooled effect (Hedges g = -0.84; 95% CI, -1.15 to -0.54; P < .001). More hours of preparation therapy were associated with greater symptom reduction (β = -0.13; 95% CI, -0.24 to -0.01; P = .04). Hours of post-dosing integration (β = -0.02; P = .53) and total number of sessions (β = -0.01; P = .86) showed no significant association. Effects tended to be smaller the further out in time they were measured (β = 0.02; 95% CI, 0.01 to 0.04; P = .003). Nine of the 12 trials (75%) were judged to have a high risk of bias, mostly because participants and staff could tell who got the active drug.

The fine print

This was a comparison across studies, not a trial that randomly assigned people to more or less preparation, so it cannot show that preparation causes better outcomes; other differences between trials could explain the pattern. Only 12 trials and 733 people were included, and most had a high risk of bias due to unsuccessful blinding. Benefits appeared to fade over longer follow-up. This summary is based on the abstract only.

What it means

Psychedelic-assisted therapy outperformed control conditions for depressive symptoms in these trials, and trials that offered more preparation time before dosing tended to report larger improvements, though the link is suggestive rather than proven.

Evidence grade: Moderate. A meta-analysis of 12 controlled trials, but most had a high risk of bias from ineffective blinding, and the therapy-quantity findings come from across-study comparisons rather than randomized tests.

This summary is based on the study’s published abstract.