Robin L. Carhart-Harris is one of the most well-known researchers in the field of psilocybin. From Imperial College London and later the University of California San Francisco, he and his team published a long series of studies on the effects of psilocybin in the brain and its application in depression, anxiety, and related disorders.

A central idea in his work is that psilocybin temporarily reduces the activity of the default mode network (a brain network active during rumination, self-referential thinking, and negative self-images). In depression and PTSD, this network is often overactive. Temporarily loosening fixed patterns can create space for new perspectives and more flexible thinking.

In addition, Carhart-Harris investigates how psilocybin increases neuroplasticity (the brain’s ability to form new connections). This explains why the period after a session is so therapeutically important. The brain is temporarily more open to learning and reform.

Clinical studies under his supervision showed strong reductions in symptoms in treatment-resistant depression, even compared to classic antidepressants (SSRIs). Direct research on PTSD is more limited, but the mechanism of flexibility and self-compassion aligns with what is needed for trauma processing.

Carhart-Harris is sometimes interpreted too enthusiastically by the media. His own tone is more cautious: psychedelics are instruments, not miracle cures. According to him, the therapeutic context, preparation, and integration are at least as important as the substance itself.