In brief
- A randomized phase 2 trial with 104 people compared a single dose of psilocybin (25 mg) against an active placebo (niacin), both with psychological support.
- At six weeks, those who received psilocybin reduced their depression scores significantly more than the placebo group: a difference of 12.3 points on the MADRS scale.
- The result is promising but preliminary: the sample size is small, the follow-up is short, and it was conducted in a controlled clinical setting. It does not equate to open-access treatment or a “cure.”
Research on psychedelics applied to mental health has been gaining momentum for over a decade, and major depression is one of its primary focuses. A phase 2 clinical trial published in JAMA in 2023 provided some of the most discussed evidence to date: a single dose of psilocybin, administered alongside psychological support, was associated with a marked and sustained reduction in depressive symptoms compared to an active placebo. It is worth examining the data calmly, without blind enthusiasm or automatic dismissal.
The study
The work, authored by Charles L. Raison, Gerard Sanacora, Joshua Woolley, and colleagues, was a phase 2, randomized, double-blind, active-placebo-controlled trial conducted at eleven research centers in the United States between December 2019 and June 2022. A total of 104 adults with major depressive disorder participated. Half (51 people) received a single 25 mg dose of psilocybin, and the other half (53 people) received niacin, a vitamin that produces perceptible bodily sensations and serves as an “active” placebo to make it difficult for participants and evaluators to guess what each person received. In both groups, the session was accompanied by preparation and psychological support, and evaluations were performed by independent raters who were unaware of the assigned group. The primary measure was the change in the MADRS scale, a standard instrument for quantifying the severity of depression, from baseline to day 43.
What was found
In the psilocybin group, the MADRS score fell by an average of 19.1 points, compared to a 6.8-point drop in the niacin group. The difference between the two, 12.3 points (95% confidence interval: −17.5 to −7.2; p < 0.001), was statistically significant and clinically relevant. Furthermore, the improvement appeared early and was maintained throughout the six-week follow-up. Regarding sustained responses (a substantial and lasting reduction in symptoms), these were observed in 42% of those who received psilocybin compared to 11% of the placebo group. Sustained remission was 25% versus 9%, although this latter difference did not reach statistical significance in the primary analysis. Regarding safety, most adverse effects were mild or moderate and were concentrated on the day of the dose: headache (66% with psilocybin versus 24% with niacin) and nausea (48% versus 6%) were the most frequent. No serious treatment-related adverse effects were recorded.
What it means (and what it doesn’t)
These results reinforce a signal that other trials have already pointed toward: in a careful clinical framework, psilocybin can alleviate depressive symptoms rapidly and with a single administration, which is very different from conventional antidepressants, which are taken daily for months. This is hopeful data, especially for people who do not respond to standard treatments. However, honesty requires pointing out the limitations with equal clarity. This is a phase 2 study with 104 participants: a small sample for the demands of clinical research. The follow-up was short—six weeks—so we do not know how long the improvement actually lasts or if the dose would need to be repeated. The use of an active placebo helps, but “unblinding” remains a challenge: the subjective effects of psilocybin are difficult to hide, and each person’s expectations can influence the response.
There is a nuance that should not be overlooked. In these trials, the substance is not administered in isolation, but within a framework of psychological support, with prior preparation, a supervised session, and subsequent integration sessions. The effect being studied is that of the whole, not an isolated pill. Extrapolating these findings to autonomous use, without context or support, is not supported by the data. That is why the authors themselves speak of a “promising” path that requires phase 3 trials, which are larger and longer, before drawing firm conclusions or considering regulatory approval.
In the legal arena, psilocybin remains a controlled substance in most countries, including Spain, although several regulatory agencies have granted it “breakthrough therapy” status to accelerate its research. We note this as an objective fact, without moralizing: the legal status of a molecule does not determine its therapeutic value or its real risk, which depend on the context, the dose, the person, and the support. The reasonable takeaway is twofold: science is advancing and deserves attention, and at the same time, it is worth resisting both the “miracle” narrative and the “absolute danger” narrative. Neither does justice to what the available trials show, with all their insights and caveats.
Source
- Raison CL, Sanacora G, Woolley J, et al. Single-Dose Psilocybin Treatment for Major Depressive Disorder: A Randomized Clinical Trial. JAMA, 2023. DOI: 10.1001/jama.2023.14530
Educational content written from a harm reduction perspective and with respect for individual freedom. It is not a substitute for advice from a healthcare professional and is not intended to encourage or condemn any drug use.
