What are psychedelic drugs?

Over the last decade, scientists have rediscovered psychedelic drugs - both as tools to research the inner workings of the brain, and as ways to treat some of the most serious mental health conditions. But what actually are psychedelics, and what do they do? University of Liverpool epidemiologist Suzi Gage is the expert - she’s the author of the book Say Why To Drugs, and explained to Phil Sansom...

Suzi - I think broadly when people talk about psychedelics, they're talking about what we refer to as the 'classical psychedelics' - these are LSD, psilocybin (which is the active compound in magic mushrooms), DMT (which is sometimes known as ayahuasca) - but there are other psychedelic substances as well. Mescaline is another one which is found in cacti. Some people say that cannabis can induce perceptual changes. Ketamine and PCP, which are dissociative anaesthetics, can induce hallucinations and things like that. Maybe even MDMA as well.

Phil - Right, that's quite a lot of drugs... why are they all linked together under this label, then, of 'psychedelic'?

Suzi - Well, the term psychedelic is thought to have been coined in the fifties by a British psychiatrist, and it's from Greek. It translates roughly as 'mind manifesting'. It became more widely used in the 60s; Timothy Leary in particular, who you've just mentioned, was a big advocate of the term. And so psychedelic substances became linked with a whole psychedelic culture, linked to music and an aesthetic as well.

Phil - What does one of these psychedelic trips actually feel like? I mean, to the best of your knowledge?

Suzi - Yeah, I mean that's a really good question, because when we think about taking a psychoactive substance, so a recreational drug... we might all understand what it feels like to be intoxicated on alcohol, and if you see someone else intoxicated on alcohol, they have quite a lot of signs that you can see what that looks like.

Phil - Sure, singing Three Lions for example.

Suzi - I was going to say, there's lots of those people on the news right now! Psychedelic intoxication is very kind of personal and inward facing. It can cause perceptual changes; people report visual hallucinations, patterns moving; synaesthesia, where two senses become connected; it can also have an emotional impact, so it can impact on how you feel about who you are; it can bring memories or feelings to the surface. But it's quite a hard thing to describe. When I wrote the book I interviewed people about their experiences; someone said, "trying to describe it is like trying to describe colour to someone who's never been able to see."

Phil - Is it a good experience or is it a bad, scary experience?

Suzi - I think it can be both - and potentially even in the same experience can be positive and negative. That's what people that I spoke to, people that I interviewed... how they described it to me is that sometimes they had quite negative experiences. One person said at one point she felt like she might've seriously damaged her mental health and she wasn't going to come back from it, which sounds absolutely terrifying. But people when I spoke to them were also at pains to say that even when they had a negative experience, they actually got quite a lot out of that after they were no longer intoxicated.

Phil - How do you mean?

Suzi - Like, understood themselves better perhaps after these experiences? I mean, some people had bad experiences and didn't enjoy it and would never do it again as well - it's important to say that.

Phil - Is that the danger of these drugs, then - that you can have that bad experience - or are they addictive as well?

Suzi - Well, they don't seem to be addictive in terms of the way we think about a substance becoming dependence-forming, let's say. So obviously you can be addicted to anything if it negatively impacts on things like your work or your home life, if you become so determined to take it regularly and it throws your life off kilter; but with quite a lot of other psychoactive substances, like think about alcohol and tobacco, these are dependence-forming. So you get a physical or mental dependence on them, as well as this potential to be addicted in the more broad sense. And psychedelics don't seem to have that at all. They also don't seem to have... or seem to be a far lower risk in terms of toxicity. If you take too much alcohol, for example, you can be very ill or it can be fatal. And that doesn't really seem to be the case with psychedelics; you'd have to take an extremely, extremely large amount, probably an impractically large amount, to experience toxicity from these substances. But as we've said, that doesn't mean that they're safe. The unpleasant effects from psychedelics are more likely to be mental than physical. Although having said that, it's also important to point out that there is the potential for injuries from behaviours undertaken while intoxicated, as is also the case for things like alcohol as well.