Neuroscientists use “neuroplasticity” for an induced change in brain function or structure, a low bar that learning anything new also clears (Carhart-Harris et al., 2026). The same 2026 paper cautions that many plasticity markers reflect learning processes that can also lock in unhelpful habits, so a marker is not proof of better mental health.
The psychedelic evidence is mainly from cells and rodents. A 2018 study found that psilocin, DMT, LSD and other drugs promoted the growth of neuron branches in cultured rat neurons (Ly et al., 2018). In 2021, one dose of psilocybin raised dendritic spine density and size in the frontal cortex of mice by about 10% within 24 hours (Shao et al., 2021). A 2026 rat study, by contrast, found lasting functional changes months later but no difference in synaptic density (Kramer et al., 2026).
How it happens is disputed: one 2023 study points to 5-HT2A receptors inside neurons (Vargas et al., 2023), another to direct binding to the BDNF receptor TrkB (Moliner et al., 2023). In people, brain scans show changes in connectivity, but no study has shown lasting structural rewiring.
Sources
- Carhart-Harris et al., 2026, Frontiers in Neuroscience: what plasticity means
- Ly et al., 2018, Cell Reports: psychedelics promote structural plasticity
- Shao et al., 2021, Neuron: psilocybin and dendritic spines in mice
- Kramer et al., 2026, Neuropsychopharmacology: psilocybin in rats months later
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