What does psilocybin do to your brain health?

Psilocybin shows antidepressant effects in early clinical studies, including phase 2 trials, that can last for months after just one or a few sessions. Notably, this also works in people who do not respond to conventional antidepressants. Multiple reviews confirm this pattern, although large-scale long-term studies are not yet available.

How psilocybin achieves this is becoming increasingly well understood. In the body, psilocybin is converted into an active substance that binds directly to a receptor for a brain-cell hormone that normally stimulates the growth of new brain connections. That binding is far stronger than with conventional antidepressants. Note: the researchers who discovered this have filed a patent on it, which increases their financial interest in the finding.

In addition, psilocybin alters the activity of a brain circuit involved in rumination and negative self-reflection. The brain temporarily becomes more flexible and less locked into fixed patterns. This is associated with fewer negative thought loops in depression, but how long that lasts and whether it is the decisive factor remains unclear.

Animal studies provide indications that psilocybin also promotes the growth of new branches and contact points between brain cells, particularly in areas involved in decision-making and memory. How strong this effect is in humans is not yet known. Effects on inflammatory substances in the brain and possible protection against Alzheimer's disease have so far been observed exclusively in animals and are purely speculative for humans.

Psilocybin always produces intense psychedelic experiences at therapeutic doses. In clinical studies these are guided by trained professionals, and the risks are manageable in that context. Outside that setting, or in people with a personal or family history of psychosis, the risks may be greater. Little is yet known about safety with long-term or repeated use.