Research
What a small study found after first psilocybin use
2026-10-19 ยท 2 min read
A first psychedelic experience can produce striking changes in brain activity. A small study published in Nature Communications on 5 May 2026 examined which changes were still detectable a month later.
What the researchers measured
Twenty-eight healthy volunteers with no previous psychedelic experience received 1 mg of psilocybin, followed a month later by 25 mg. The order was fixed. Researchers used EEG during the sessions and MRI before and after them.
After 25 mg, EEG recordings showed greater signal complexity at one and two hours. At the one-month follow-up, diffusion MRI showed reduced axial diffusivity, a measure of water movement, in some pathways connecting frontal and deeper brain regions.
That measurement does not directly show new neural connections or physical thinning of brain tissue. The paper reported that lasting functional brain changes were largely absent.
What it tells us
Some brain measurements were associated with changes in reported well-being. These relationships offer questions for further research; they do not establish that a particular brain change caused the improvement.
The small sample, fixed treatment order and healthy participants also limit what this study can tell us about treating depression or other conditions.
For a broader introduction to study design, see our clinical trial phase guide.
Source: T. Lyons and colleagues, Human brain changes after first psilocybin use. This is a plain-language summary of the original research, available under CC BY 4.0.
Explore the research map
Find study listings and follow their links to the original registry records.
Open the research map