How to Change Your Mind: The New Science of Psychedelics Michael Pollan Allen Lane , pp. 480 , £

When Peregrine Worsthorne was on Desert Island Discs in 1992, he chose as his luxury item a lifetime supply of LSD. He may, according to the American journalist Michael Pollan’s fiercely interesting new book, have been on to something.

Acid has a bad name these days: either a threat to the sanity of your children, or a naff 1960s throwback favoured by the sort of people who sell you healing crystals at markets in Totnes. Yet in LSD-25, psilocybin, DMT, mescaline and others we have a family of molecules with startlingly powerful effects on the human mind. They are not addictive, carry little or no physiological risk, and their association with the desire to jump out of windows has been distinctly exaggerated. They might even be good for us.

They have done much to shape the world we live in. In addition to their role in the 1960s counterculture they have a pretty large place in the history of Silicon Valley, and a seldom-acknowledged role in the formation of Alcoholics Anonymous (Bill Wilson, AA’s founder, credited the ‘spiritual experience’ that first got him sober to a trip on belladonna, and in the 1950s pressed for LSD to be used in treating alcoholics).

Yet they are very hard to pin down. ‘Set and setting’ (i.e. circumstance and expectation) profoundly influence what happens when you take them, and their effects are highly subjective. They are an ouroboros of an observer’s paradox, worming their way between the territories of cognitive science, psychoanalytic theory and the anthropology of shamanism.

What to call them? The psychiatrist Humphry Osmond minted the word that stuck (psychedelic, or ‘mind-manifesting’) in a 1956 exchange of letters with Aldous Huxley (who favoured phanerothyme: ‘spirit-manifesting’). But they’ve also been seen as psychotomimetics (simulating the effects of psychosis), psycholytics (mind-loosening; bringing unconscious thoughts to light), and (Osmond again, unsuccessfully) psychodelytics. In an effort to reclaim them from the counterculture, some scholars in the 1970s started calling them entheogens (‘generating the divine within’) to reconnect them with their ancient spiritual roles.

Aside from a hair-raising excursion into toad venom, Pollan sticks mostly to psilocybin and LSD — as being the compounds that have received most scientific attention and are easiest to obtain. And he doesn’t write very much of distinctions between psychedelics (Grace Slick once remarked that ‘acid is like being sucked up through a tube; DMT is like being shot out of a cannon’).

Nevertheless, he goes to the heart of the commonalities. A high-dose LSD or psilocybin trip seems pretty reliably to bring about what even atheists recognise as a mystical or spiritual experience: a dissolution of the ego; a sense of connection to a wider cosmic order. Most interestingly — and Pollan navigates in part by William James’s description of spiritual experience — these episodes have the quality of being ‘noetic’: you return from a trip (unlike, say, a dream) unshakeably convinced that the intuitions you experienced were in some important way real.

This is one problem. People become evangelical about them. It seems obvious that these molecules have something very interesting to tell us: it just may not be what the people who’ve taken them think it is. Pollan does his best, in this even-handed, spry and multidisciplinary popular book, to make sensible approaches to an answer. He sketches out the history, interviews current and former researchers, historians and practitioners of psychedelic therapy (some of them wacky; others refreshingly prosaic), and also takes a few trips himself for a section he calls his ‘travelogue’.

The other problem the data present is that trips share another of the marks of mystical experience described by James: ineffability. That is, you may be sure you’ve had a significant experience, but words don’t seem to do it justice. One philosopher reported: ‘I felt as if I had been repeatedly sucked into the asshole of God.’ Another psychonaut, struck by a powerful epiphany, demanded her guides write it down: ‘Eat right. Exercise. Stretch.’ Aldous Huxley talked about ‘the realisation... of Love as the primary and fundamental cosmic fact’, which he admitted ‘must [...] seem like twaddle. But the fact remains.’ As the 1960s chair of Harvard’s psychology department put it in a memo critical of Timothy Leary’s work: ‘Many reports are given of deep mystical experiences, but their chief characteristic is the wonder at one’s own profundity.’

Ah, Leary. Publicity-crazed, perma-grinning Timothy Leary was the worst possible ambassador for psychedelics. Not only did his stunts contribute substantially to the atmosphere in which governments cracked down both on street use and clinical research, his fame occluded the serious work that has been done on them before and since.

It’s not widely known, for instance, that between Albert Hofmann’s famous bike ride in 1943 and the mid 1960s there were more than 1,000 scientific papers on them, with promising indications that psychedelic experiences might be of use in treating addiction, depression, obsessive-compulsive disorder, and the fear of death in those with terminal diagnoses. But, as Pollan puts it delicately, many of these studies get ‘compromised by the enthusiasm of the researchers themselves’.

Pollan is careful — or semi-careful — not to succumb to that sort of enthusiasm himself. He’s properly sceptical, for instance, about Terence McKenna’s ‘stoned ape’ hypothesis, which suggests that human consciousness itself was kick-started by the entry of psilocybin mushrooms into the early hominid diet. And at each turn he’s careful to offer the weaker (or what he calls more ‘parsimonious’) claim in place of the stronger one.

So he wryly acknowledges the speculation that consciousness might be a property of the universe, and that the human mind, rather than originating it, might be — as the philosopher Henri Bergson expressed it — something like a radio receiver. But he sticks to the weaker claim, which is interesting enough. These molecules seem to act to suppress a brain structure known as the ‘default mode network’, which is associated with the sense of self, or ego. It is the DMN — undeveloped in young children and other animals — that guards the doors of perception.

Think of the DMN as the bossy head-prefect of your brain: it makes sure the other sections stay at their different lessons. Lock it in a cupboard in the boot room for eight hours, though, and it’s chaos in the school corridors. Neurones fire together all over the brain (hence the sense of a world infused with meaning; and the frequent experience of synaesthesia). Not much gets done — the brain is in a ‘high-entropy’ state — but a lot of unexpected new friends are made, and those friendships, just as in The Breakfast Club, last.

This strays suggestively into territories mapped by the work on cognitive biases offered by Kahneman and Tversky, and on the ‘lantern consciousness’ Alison Gopnik describes in infants. Essentially, everyday waking consciousness may be the most adaptive, and most computationally efficient, way for an adult to go through the world; but it’s not the only one. As Gopnik puts it: ‘The short summary is, babies and children are basically tripping all the time.’

Pollan quotes Chekhov’s line: ‘If many remedies are prescribed for an illness, you may be certain that the illness has no cure.’ Then he cleverly inverts it: if one remedy is prescribed for many illnesses, ‘it could mean those illnesses are more alike than we’re accustomed to think’. That is, many illnesses that psychedelics seem to help may share qualities to do with getting trapped in self-reflective mental loops: too strong and well-defended a sense of self; too bossy a head prefect. We fall into cognitive ruts; some of them harmful. Psychedelics can shake us out of them.

As much as Pollan may think that the mainstreaming of psychedelics could be a good thing for the treatment of all sorts of psychological conditions, he’s upfront about the difficulties. Quite apart from the cultural stigma, the institutional obstacles are formidable. Who’s going to fund the widespread testing necessary to secure regulatory approval?

There’s not much upside for drug companies, given that LSD’s patent has long expired and psilocybin mushrooms grow in the ground. The tests themselves will be bedevilled by all sorts of replicability, dosage and blinding issues, given that results are powerful, highly subjective, massively influenced by set and setting, very tricky to quantify and are triggered by close-to-homeopathic dosages of the magic molecules. And even if approved, a nearly cost-free ‘medicine’ that you take once or at most a handful of times doesn’t offer much of a business model.

And yet. Trials, here and there, are going on. And Pollan’s Epilogue describes the 2017 Psychedelic Science convention, where a plenary panel on ‘The Future of Psychedelic Psychiatry’ included a former Head of the American Psychiatric Association and the former head of the National Institute for Mental Health. The mental health establishment is, for better or worse, starting to open its mind.