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Science
May 10, 2026
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Single Dose of Magic Mushroom Psychedelic Can Cause Anatomical Brain Changes, Study Finds

AI Summary
A study by Imperial College London shows that a single 25 mg dose of psilocybin can produce measurable anatomical changes in the brain that persist for at least a month, linking structural plasticity to improved wellbeing. The findings offer new mechanistic insight into how psychedelics may treat mental‑health disorders, though larger trials are needed.

The Lead

Researchers at Imperial College London have shown that a single 25 mg dose of psilocybin can produce detectable anatomical changes in the brain that persist for at least a month, offering fresh clues about how psychedelics may alleviate mental‑health disorders.

Single Dose of Psilocybin Triggers Measurable Brain Structure Changes

  • 28 healthy volunteers with no prior psychedelic experience participated.
  • Participants received a low “placebo” dose (1 mg) followed, a month later, by a full psychedelic dose (25 mg).
  • Brain activity was monitored with EEG, functional MRI, and diffusion tensor imaging (DTI).

Diffusion Tensor Imaging Reveals Reduced Nerve Tract Diffusion

One month after the psychedelic dose, DTI scans showed a drop in water diffusion along front‑to‑mid‑brain nerve tracts, suggesting either pruning of existing fibres or growth of new, unmyelinated connections. The same participants also exhibited a surge in EEG‑measured brain entropy within an hour of dosing.

Potential Ripple Effects on Psychedelic Therapeutics

The anatomical shift mirrors patterns seen in ageing and dementia—where diffusion typically increases—hinting that psilocybin may promote a rejuvenating “entropic brain” state. Researchers linked the magnitude of entropy spikes to deeper psychological insight and improved wellbeing, reinforcing the hypothesis that structural plasticity underlies therapeutic outcomes. Senior author Robin Carhart-Harris described the result as “remarkable”.

What This Means for Future Psychedelic Research and Treatment

  • Larger, longitudinal studies are needed to confirm durability of the changes.
  • If replicated, DTI could become a biomarker for assessing psychedelic efficacy.
  • The findings may accelerate clinical trials targeting depression, anxiety, and addiction.

While promising, the study’s small sample size and indirect imaging methods warrant caution, but the evidence moves the field closer to a mechanistic understanding of psychedelic‑induced neuroplasticity.