Will Psychedelics and Hallucinogens Revolutionise Psychiatry? – Conversations with Prof David Nutt

Posted on: April 2, 2021
Last Updated: February 7, 2023

Dr Sanil Rege talks with Prof David Nutt, an expert in the field of psychedelic research.

Prof David Nutt is a researcher, policy adviser, author, and currently head of Neuropsychopharmacology at Imperial College London and Chair of the Charity Drug Science. Prof Nutt uses brain imaging research to explore the effects of drugs in the brain and the mechanisms of disorder such as addiction and depression.

Under his leadership, the psychedelic research group at Imperial  College has become one of the world’s foremost psychedelic research laboratories, publishing landmark research on psychedelic neuroscience and developing new therapies for mental illness. Prof Nutt was previously chair of the UK Advisory Council of the Misuse of Drugs.

He has held many leadership positions in both UK and European academic, scientific, and clinical organisations, including presidencies of the European Brain Council, the British Neuroscience Association, the British Association of Psychopharmacology and the European College of Neuro-Psychopharmacology.  In 2013, he won the John Maddox Prize from Nature Sense about science for standing up for science. And in 2017, a doctor of laws on Kasa from the University of Bath.

Dr Sanil Rege is a Consultant Psychiatrist and founder of Psych Scene and Vita Healthcare.

Psychedelics are any of the so-called mind-expanding drugs that can induce states of altered perception and thoughts, frequently with a heightened awareness of sensory input but with diminished control over what is being experienced. [Rucker J et al., 2018]

Hallucinogens are not classified as ‘psychosis inducers’ but instead are classified by their chemical structure, pharmacological mechanism of action, and clinical properties [Romeu et al. 2016]:

  • Classic Psychedelics
  • Empathogens/Entactogens
  • Dissociative Anaesthetics


The biggest limitation is going to be doctor education, which actually I think is why this interview you just done is spectacular, because we’ve gone through everything, all the issues that doctors confront me with when they’re trying to find reasons not to think positively about this treatment. 


The first is that the depressed people, when they go through the trip, they often see the reasons why they’re depressed. For the first time maybe ever. They’ve understood why they’re depressed. And of course, the other thing about them is that they can open the mind to new solutions so people can think differently. People can sometimes come to terms with their abuser, for instance, in a trip and actually get closure. So I prefer the term psychedelic to hallucinogenic.


I think the reason that drugs like psychedelics produce enduring changes in people’s view of themselves in the world is because they also do stimulate neuroplasticity. One of the key aspects of this 5HT2A receptor is that it seems to control pyramidal cells activity which is intimately related by the number of synaptic spines they have, the number of inputs they have. And there are other studies now recently showing that LSD, psilocybin do increase the growth of synaptic spines, probably through a BDNF process as well.


Well, let me explain the process we are using in our clinical trials. So which is likely to be pretty similar to what ends up in clinical practice. And there are four key elements. The first is what we call the preparation session. So you have to explain to people what’s going to go on in a trip because most of them haven’t had a trip. And you have to reassure them that even if they feel they’re going mad, they’re not and that there will always be a therapist present and help them work out how best to deal with what are often very negative experiences. I just let me just dispel one myth. One of my senior colleagues said to me once, when, of course, these people are getting over the Depression, they’re just having a fun trip. I said that might be fun for you when you were young, but for these depressed people who have often been traumatized and suffered for decades, the trip is not fun. It’s a really hard thing to do. They’re often they’re often reliving they do. They relive their trauma. They and they come. And it’s so it’s it’s hours of really difficult psychological experiences. It’s not fun at all.


Certainly psilocybin and MDMA are going to be proven therapies in psychiatry within a few years. As the first point, the second point is. I believe they’re going to revolutionize many aspects of psychiatry and I hope psychiatry will embrace them, because if it doesn’t, then we’re going to go through this period of years, maybe decades, where patients suffer. Let me give you a little sum. I’ve done a little bit of arithmetic. Before LSD was banned in 1967 in America, the US government had funded six trials of LSD, one or two doses for alcoholism. Recently, some Norwegians reviewed that, a meta analysis of that data, and they came up with an effect size of one, so it’s twice, two and a half times that of Acamprosate. So this is the biggest effect I’ve ever seen in alcoholism.

Take-home Messages

  • Despite the controversial history of psychedelic therapy, clinical studies have described the therapeutic benefits of psychedelic experiences in a safe and supportive environment.
  • Reclassification of psychedelics as a schedule II drug will enable further clinical research and the possible discovery of novel benefits of psychedelic administration in psychiatric disorders.
  • Worldwide, about 100 psychedelic trials are currently active to treat depression and anxiety in the terminally ill, alcohol and drug use disorders, dementia, anorexia and chronic pain.
  • The UK, Canada, the United States, and Israel are active research hubs, and international collaboration is informed. The first psilocybin-assisted psychotherapy trial has been approved in Australia, targeting depressive and anxious symptoms in terminal patients, and is hosted at St Vincent’s Hospital, Melbourne. [Clinical Memorandum, RANZCP]
  • In 2021, the results of phase 2, double-blind, randomised, controlled trial involving patients with long-standing, moderate-to-severe major depressive disorder comparing psilocybin with escitalopram, over a 6-week period showed no significant difference between antidepressant effects of psilocybin and escitalopram in 59 patients. [Carhart-Harris et al., 2021]
  • In Australia, from 1 July 2023, Psilocybin and MDMA can be prescribed by specifically authorised psychiatrists for the treatment of treatment-resistant depression and PTSD respectively.  However the TGA acknowledges that patients may be vulnerable during psychedelic-assisted psychotherapy, requiring controls to protect these patients. [TGA]
  • Further research is required to assess psychedelic therapies’ efficacy, safety, and effectiveness to inform future potential use in psychiatric practice.

Prof David Nutt will be speaking at the International Summit on Psychedelic Therapies for Mental Illness (17-20 November 2021)

Read More: 

1. Psychedelics and Hallucinogens – Mechanisms of action and Clinical Efficacy 

2. Psychedelic Therapy – A Beginner’s Guide

3. Evidence base for psychedelics in depression

4. Therapeutic mechanisms of psilocybin

5. Esketamine 


  1. Rucker JJ, Iliff J, Nutt DJ. Psychiatry & the psychedelic drugs. Past, present & future. Neuropharmacology. 2018 Nov 1;142:200-18
  2. Romeu et al., Clinical applications of hallucinogens: a review. Exp Clin Psychopharmacol. 2016;24(4):229–268.