The drug is banned in the UK but, in July, Australia became the first country in the world to begin prescribing psilocybin to patients with treatment-resistant depression following studies – including research by Prof Nutt – which have demonstrated a strong therapeutic effect.
Now there are hopes that it could also be used to help people overcome alcohol dependency.
“I think it’s going to revolutionise the treatment of addiction,” said Prof Nutt, who is speaking to the Herald ahead of a visit to Edinburgh on September 28 for a Science of Psychedelics event.
Prof Nutt, a neuropsychopharmacologist at Imperial College London who co-founded the world’s first psychedelic research centre at the university 15 years ago, points to recent US research published at the end of 2022.
In what is believed to be the first randomised, control trial for psilocybin in patients with alcohol use disorder, 93 participants aged 25 to 63 received either two psilocybin pills or antihistamine tablets – the placebo – along with psychotherapy.
All of the volunteers were averaging seven alcoholic drinks a day prior to the study.
By the end of the study half the psilocybin group had quit alcohol completely compared with around a quarter of those who received the placebo.
“That was such a powerful outcome that that’s going to go into a Phase Three trial,” said Prof Nutt.
“If that works – as I’m sure it will – then it’ll be a licensed medicine for the treatment of alcoholism, probably within five years.”
It comes weeks after statistics revealed that there were 1,276 alcohol misuse deaths in Scotland last year – the highest number since 2008.
Prof Nutt admits to being surprised by the potential medical benefits of psychedelics.
The 72-year-old academic has been an outspoken critic of the “war on drugs” and was sacked in 2009 as chairman of the Advisory Committee on the Misuse of Drugs (ACMD) by then-Home Secretary Alan Johnston after he denounced the government’s decision to upgrade cannabis from a Class C to Class B drug.
He has frequently argued that illicit drugs should be classified according to evidence of harm, insisting that alcohol and tobacco do more damage than LSD or ecstasy and that smoking cannabis carries only a “relatively small risk” of causing psychotic illness.
Nonetheless, he says he did not go into his current field “as a flag bearer for psychedelics in medicine”.
“I knew they were interesting drugs that changed the brain, but my group studied them because we wanted to understand what a ‘psychedelic trip’ really is,” he added.
It was only when scans showed that the psychedelics induced lasting brain changes that they team predicted that this ‘rewiring’ effect could offer hope for patients with depression who had failed on standard treatments, including antidepressants and cognitive behavioural therapy (CBT).
After nearly three years wrestling with red tape and regulators to obtain approval for a clinical trial, the team finally tested the effects of giving two oral doses of psilocybin – 10mg to check for side effects and the full 25mg seven days later – to 12 patients with treatment-resistant depression, who also received psychotherapy. An additional eight patients subsequently joined.
In some cases, the patients’ depression scores had halved within a week – sometimes within 24 hours.
While most relapsed within six months, nearly a decade on a few participants remain depression-free.
“We were amazed by how powerful the effect was,” said Prof Nutt.
“These people are very difficult to help, but it was remarkable – they all got better, some of them are still well.
“The effect of that single dose of psilocybin, over six months, was the most powerful one-off treatment ever in treatment-resistant depression.
“That’s why it’s seen as a revolution in psychiatry for resistant-depression, and it’s now being seen as a potential revolution in treatment-resistant disorders like addiction as well.
“It could transform the landscape of psychiatry. I think these are the most important innovations in psychiatry for 50 years.”
Prof Nutt said that while some patients would be understandably wary of a psychedelic trip, the effect appears to “reset” the brain so that people with troubling thought loops can “think differently about things” and benefit more from counselling.
He anticipates similar benefits in patients with eating disorders, ADHD, and obessive-compulsive disorder.
He added: “The banning of psychedelics has achieved no health benefits at all – all it did was just to deny access to these drugs for 55 years to people who have otherwise died of illnesses, addictions, suicides.
“It’s been the worst censorship of research in the history of the world.”
Tickets for Science of Psychedelics are available here