Imperial College London

Imperial College London’s psychedelic research brought brain imaging and clinical investigation into the study of altered consciousness. At its Centre for Psychiatry on the Hammersmith campus, a team led by Robin Carhart-Harris worked in David Nutt’s lab to examine what happens in the brain during psychedelic experience. The program began with psilocybin imaging in 2009 and later moved from mapping brain activity toward testing whether psilocybin could help people with treatment-resistant depression.

Research setting and origins

The work took place in a recently completed complex on Imperial College London’s Hammersmith campus in West London. The Centre for Psychiatry’s glass-walled walkways and doors opened by identification helped mark the setting as a modern research laboratory, but the project itself depended on an unusual alignment of people and support: Nutt’s psychopharmacology laboratory, Carhart-Harris’s developing research career, and funding from Amanda Feilding.

Carhart-Harris had approached Nutt in 2005 hoping to study psychedelics and dreaming. His proposal initially seemed far-fetched to Nutt, who noted that the young researcher had no neuroscience experience. Nutt nevertheless offered him a PhD, beginning with a more conventional project on MDMA’s effects on the serotonin system, with the possibility of turning to psychedelics later. By 2009, Carhart-Harris had completed his PhD and was working in Nutt’s lab. Funding from Feilding helped make the proposed psychedelic research feasible, and the team received permission from the National Health Service and the Home Office to study psilocybin’s effects on the brain.

Brain imaging and an unexpected result

The initial project combined administration of psilocybin with functional magnetic resonance imaging and magnetoencephalography. These scanning methods allowed researchers to track brain changes while volunteers underwent the drug’s effects. The aim was to connect reported experiences, including hallucination and self-dissolution, with measurable patterns of activity rather than treating the experience as inaccessible to neuroscience.

Carhart-Harris volunteered to be the first participant, reasoning that it would be fair to undergo the procedure before asking others to receive the drug in a scanner. Nutt discouraged him. Carhart-Harris described himself as anxious and possibly not in the best psychological position, and Nutt also worried that taking part could compromise his objectivity. A colleague therefore became the first volunteer to receive an injection of psilocybin and enter the functional magnetic resonance imaging scanner.

The first results overturned the team’s expectation. Carhart-Harris had anticipated increases in brain activity, especially in regions associated with emotion, and thought the pattern might resemble the dreaming brain. Earlier work by Franz Vollenweider had also indicated increased activity, particularly in the frontal lobes. Instead, the Imperial team found reduced blood flow, one measure used as a proxy for brain activity. A second measure, based on oxygen consumption, supported the initial result. The researchers concluded that psilocybin reduced activity, with the decrease concentrated in the default mode network, a brain network Carhart-Harris had not previously known much about. The finding gave the laboratory a physiological lead for investigating how changes in brain activity might correspond to changes in conscious experience.

From laboratory research to depression treatment

After developing his account of the brain’s response to psychedelics, Carhart-Harris sought to test its implications with patients. This marked a change in the lab’s work: it expanded from basic research into a clinical application. Nutt secured a grant from the U.K. government for a small pilot study of psilocybin for treatment-resistant depression, a condition in which patients had not improved with usual therapeutic approaches and medications.

The feasibility study, whose initial results appeared in Lancet Psychiatry in 2016, enrolled six men and six women. Each had already tried at least two treatments without success. There was no control group, and all participants knew they were receiving psilocybin, so the study could not provide the kind of comparison a randomized controlled trial would offer. Its findings were nevertheless notable: after a week, all twelve participants showed improvement, and two-thirds were depression-free, some for the first time in years. Seven still showed substantial benefit three months later.

The study was expanded to include twenty participants. At six months, six remained in remission, while the others had relapsed to varying degrees, raising the possibility that treatment might need to be repeated. The research was modest in scale and not randomized, but it found that psilocybin was well tolerated in this group, with no adverse events reported, and that many participants experienced marked, rapid benefits. Those limits and outcomes mattered together: the results suggested promise without establishing a definitive treatment effect.

Institutional reach and significance

Imperial College London’s work linked a neuroscience laboratory to a developing clinical research program. The imaging studies sought physical correlates for experiences that had often been described in psychological, spiritual, or subjective terms; the later depression study tested whether the same research environment could investigate potential therapeutic use. The shift did not erase the distinction between those aims. Brain scans offered a way to study changes during the psychedelic state, while the pilot asked whether those changes could be associated with improvement in a defined patient group.

The depression findings also reached beyond the laboratory. In 2016, the European Medicines Agency considered evidence that included Imperial College London’s feasibility study, alongside results from research at Johns Hopkins and New York University. Although regulators pointed out that existential distress was not an official diagnostic category, they saw a signal that psilocybin might help treat depression and suggested a larger, multisite study. Imperial’s small trial thus contributed to a broader regulatory and scientific discussion: it helped move the case for further research from a hypothesis about the brain toward a testable clinical question, while leaving the need for larger and more rigorous trials clear.