Two reasons why I’m skeptical about psychedelic science

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Since childhood, I have been intrigued by altered states of consciousness, such as out-of-body experiences, paranormal phenomena and religious visions. To better understand how these experiences come about, I studied psychology and neuroscience. And in my scientific career I have focused on why some people are more susceptible to these experiences than others.

When I came across psychedelic science a few years ago, this field naturally piqued my academic interest as well. This was an opportunity to study people who had had a psychedelic experience and who claimed to have glimpsed ultimate reality. I started researching psychedelic experiences at Leiden University and founded the PRSM lab – a group of scientists from different academic backgrounds who study psychedelic, religious, spiritual and mystical experiences.

Initially, I was excited about the mind-altering potential of psychedelics. When administered correctly, these substances seem to improve people’s mental and physical well-being. They also increase feelings of connection and care for the environment.

Psychedelic therapy has been shown to have great potential for treating a wide range of conditions, including depression, anxiety, addiction and post-traumatic stress disorder. This enthusiasm about the potentially transformative effects of psychedelics has been reflected in positive media attention to this topic in recent years. Michael Pollan, an American author and journalist, has brought psychedelics to an audience of millions with his book and Netflix documentary.

However, my initial optimism about psychedelics and their potential has turned into skepticism about the science behind much of the media hype. This is the result of a closer examination of the empirical evidence. Yes, at first glance it seems like psychedelic therapy can cure mental illness. But on closer inspection, the story is not that simple.

The most important reason? The empirical evidence for the efficacy of and mechanisms of action underlying psychedelic therapy is far from clear.

Two issues

Together with my colleague Eiko Fried, I have written a critical review article listing the problems with current clinical trials of psychedelic therapy. The main concern is called the “breaking blind problem”. In psychedelic studies, patients easily find out whether they have been randomly assigned to the psychedelic or placebo group simply because of the profound mind-altering effects of psychedelic substances.

This breaking of the blind can actually result in a placebo effect for patients in the psychedelic group: they finally get the treatment they were hoping for and they start to feel better. But it can also result in frustration and disappointment for patients assigned to the control group. They hoped for a miracle cure, but now find out that they have to take a placebo pill for six hours with their therapist.

As a result, any difference in therapeutic outcomes between the psychedelic group and the placebo group is largely due to these placebo and nocebo effects. (A nocebo effect occurs when a harmless treatment causes side effects or worsens symptoms because the person believes they might occur or expects them to occur.)

Knowing who got what also affects therapists, who may be motivated to get more out of the therapy session if their patient is getting the “real deal.” And this problem is impossible to control in so-called randomized controlled trials—still the gold standard for evaluating the effectiveness of drugs and treatments.

Nonclinical research into psychedelics also has its problems. You may recall the graph of a brain on psilocybin compared to a brain on a placebo (see below). Psilocybin increases connectivity between different brain regions, which is shown as a colorful series of connecting lines.

This has become known as the ‘entropic brain hypothesis’. Psychedelics make your brain more flexible, so it returns to a childlike state of openness, novelty and surprise. This mechanism is thought to underlie the effectiveness of psychedelic therapy: by “freeing your brain,” psychedelics can change ingrained and maladaptive patterns and behavior. However, it turns out that the picture is much more complicated than that.

Psychedelics constrict the blood vessels in your body and brain, causing problems when measuring brain signals with MRI machines.

The entropy brain graph may simply reflect the fact that blood flow in the brain changes dramatically under psilocybin. It is also far from clear what entropy actually means – let alone how it can be measured in the brain.

A recent study on psilocybin, which has yet to be peer-reviewed, found that only four of twelve entropy measurements could be replicated, casting further doubt on the applicability of this mechanism of action.

While the mind-freeing story of psychedelics is compelling, it doesn’t yet fit well with the available empirical evidence.

These are just two examples that illustrate why it is important to be really careful when evaluating empirical studies in psychedelic science. Don’t take findings at their word, but ask yourself: is the story too good or too simple to be true?

Personally, I have developed a healthy dose of skepticism when it comes to psychedelic science. I am still intrigued by the potential of psychedelics. They offer great tools for studying alterations in consciousness. However, it is too early to draw any definitive conclusions about their mechanisms of action or their therapeutic potential. For that, we need more research. And I am happy to be a part of that endeavor.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Michiel van Elk receives funding from the Netherlands Organization for Scientific Research (NWO; grant ID# VI.Vidi.191.107).

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